Is this possible?  (I think so?)
Is it difficult? (I think just replace the socket, maybe the wiring?)
Any special concerns / issues?

Thanks in advance!

not 100% sure but would think you'd just need to replace the socket/switch.

OK, I think what you're asking is this:

You have a single fixture rated for a maximum 60-watt lamp, currently controlled by one wall switch.

You want the maximum wattage rating upped, and you want it controlled by 2 or more switches, such as in a room with 2 or more entries so you do not have to walk across the room to switch the light on/off.

Is this what you're asking?

If so, it is fairly easily done as long as you can safely run wire and do simple electrical.

The first thing to do--as with any electric service of any nature if you're not a professional--is to find the breaker controlling the circuit the light is on and shut it off.  From there, pull the fixture and switch out of the wall, BUT DO NOT DISCONNECT ANY WIRING!  Using a tester (preferrably a "non-contact" type that lights and/or beeps when brought within a few inches of a live electrical circuit), verify that all power is "open" (off).  

This next part is critical, so pay attention if you want to avoid a buttload of frustration, posting here two-dozen times asking questions, or spending $65 an hour for a professional to come out, fix your crap, and laugh at you on their lunch breaks (yeah, I've done my share of service calls, LOL).  

Don't take any wires apart!  Get a piece of paper and draw a sketch of what wires go where, which wires enter which box, what colors they are, and etc.  Depending on the age of the home, your wires may be anything from hook and loop to Romex to MC.  I need to know this:  Which wires are bundled in the back of the box and not attached to any device; how many there are; if they are clad in metal, bare, carboard, or plastic; and all the colors.

Pictures are, of course, the very best way to do this, but we can also do it with a scanned sketch or just with you being very articulate about what you've observed.  What I need to determine is the location of the switch-and-feed:  Where power comes in, and to which box.  It may come in at the fixture and backfeed to the switch, or it may come in at the switch and then feed the fixture.  Depending on which of these scenarios is true, I can then walk you through the process.  

The rest is cake, and you can do it yourself very easily.  You'll need access to your attic or crawlspace, or you'll need very good sheetrock patching skills.  I'll tell you which wire to run, how to run it, and how to hook it up.  

As far as the fixture itself, you'll just have to buy a fixture rated for whatever wattage you'd like in the style you'd prefer (if married, the style the wife demands, of course ).

Fishing wire from a box through a top plate can be tricky.  I'm impatient, and I'm damn good at patching sheetrock, so I just cut a slot under the top plate, drill from the room into the attic, and fish my wire that way.  The location of the new switch is easy, as you'll be cutting a hole for the switch box, anyway.  Done right, and with overhead/underneath access to run the wire, you'll only have 1 small strip about 2" wide and 4" long to patch.  Or I rip the old box out and replace it with a new cut-in box and avoid all patches all-together.  The choice is yours.  

The switches you'll need to buy are called "3-way" switches if there are 2 switched locations, and "4-way switches" if there are three or more switches controlling the fixture.  The switches need to be rated the same size as the breaker, so don't get 15A rated switches for a 20A circuit just to save a buck or two a switch.  You'll also need to decide if you want to install dimmers or timers, as those are completely different animals than toggle switches as they are rated for the wattage used, rather than the amps provided.  It makes no difference on the fixture end, just the dimmer/timer end.  

You need to determine the location of any and all switches you wish to add to the circuit, as well.  Not only is this important for the obvious, such as the length of wire you want to run, but if it is excessively long (100' +) we have to account for voltage drop and any control wiring for electronic dimmers/timers.  

It is important you carefully examine the desired locations.  We have to avoid things that are obstacles or potential obstacles/dangers, such as chimney chases, AC soffits, wire and plumbing chases, and etc.  Last thing you want to do is start cutting holes only to find out you can't fish a wire or you hacked into water or vent lines, an HVAC duct, or cut through a bunch of wires.  Fail to plan, plan to fail, and all that riggaramoe.  

In conclusion, YES, this is definately a fairly easy job:  I give it a 3 or a 4 on a 10 scale.  Cost-wise, it'll be well under $50, not including the fixture you choose, as those can be $10 - $500.  Time-wise, figure a Saturday - maybe as little as 3 hours or as many as 8, depending on all the variables.  To have a licensed electrician do this, you'd be looking at about $400 not including any sheetrock patching.  

The more pictures and descriptions you can provide me, and the more detailed they are, the easier I can walk you through this and the less hassle for you.  

Is it just 1 switch and 1 fixture right now?  Are you wanting to add a second switch only, or maybe more than 2 switches total and more fixtures?  What do the wires look like, and how are they terminated and landed in the box and on the device(s)?  Can you take pictures of the room, and show where you'd like the new switches and fixtures?  

God, I LOVE doing this shit!  I'm as giddy as a schoolboy with a substitute teacher in a mini-skirt who just dropped her papers off the desk.  

Upon further review, it would seem you just want to replace the fixture itself from a single-lamped 60-watt maximum to a 2- or 3-lamped fixture rated higher than 60 watts.

Is this the case?

If so, it's only a matter of replacing the fixture unless it is currently on a dimmer or timer.  Dimmers and timers are rated for wattage and amperage, so let's say you wanted 3, 100-watt lamps.  Your dimmer/timer would have to be rated at 125% of 300 watts, or 375 watts.  If not rated for that, you'll need to change out the dimmer/timer so it is rated for the new fixture you install.

If in doubt of the lumens (light output) you need, plan for the maximum.  You can always put 60-watt lamps in a 100-watt fixture, but never 100-watt lamps in a 60-watt fixture.  Rate the dimmer for the maximum wattage of the fixture, not the pulled wattage.  EG:  A 4-lamp 100-watt fixture is rated at [100(4)](1.25) = 500 watts, which is standard rating for a dimmer.  Just because you use two 60-watt lamps that draw 120 watts, you still want to rate the dimmer for four lamps at 100 watts just because someone down the line may up the size or amount of the lamps.  

First, thanks to all.

Richardh: I'm far more remedial than you think.  I have a stand alone table lamp (already wife approved!).  It currently takes a 60 watt bulb, max.  I want to convert this lamp to a three-way lamp (say, 50 / 75 / 125 watt), so I can read the newspaper with my fading eyes.

I appreciate your detailed responses, but I'm WAY behind you.

Quoted: First, thanks to all. Richardh: I'm far more remedial than you think.  I have a stand alone table lamp (already wife approved!).  It currently takes a 60 watt bulb, max.  I want to convert this lamp to a three-way lamp (say, 50 / 75 / 125 watt), so I can read the newspaper with my fading eyes. I appreciate your detailed responses, but I'm WAY behind you.

Well shit.

Are you SHURE you don't want to do some remodeling?  Maybe even add a recptacle somewhere?  Change out a fluorescent ballast?  Replace a busted switch, even?  

To convert the lamp, just change the socket.  Your best bet for a selection of sockets would be an old ACE Hardware (mom-and-pop type, 1 each) or, even better, a lighting shop.  A 3-way 100-watt rated socket is about $7.  On the bottom of the lamp is a nut that holds the neck to the lamp shade bracket.  After taking that apart, the cord will pull through when you remove the socket, which is usually either crimped in or held in with set-screws.  Some are simply pressure set, which is like a crimp but tapered instead so no crimp is necessary.

Remove the two wires, snip the ends and re-strip, then land them on the new socket and reverse the take down procedure.  Make sure you loop the wire the direction the screws tighten (clockwise) so you don't de-strand the wire when tightening the screws.  

Best bet is to remove the existing socket and take it with you just to make sure you get a matching one for mounting.  Most are universal, but you never know and it might save you a trip.

Sorry I misunderstood your question and wasted your time reading all that drivel that doesn't apply to your question.  I can't physically be an electrician any longer due to a disability, so I asked GoatBoy to get this forum started so I could still participate by helping others learn to DIY.  

I tend to get excited because this forum has all 3 of my favorite elements:  1, I love to write, and many questions are best answered in long, detailed explanations; 2, I love to help people and educate them, and putting my experience to use to empower people to save money, do a better job, and have pride in their work is extremely rewarding; and, 3, it allows me to still feel useful--albeit in a limited way--and keep up on my construction terminology, look up code to stay current, and challenges my mind to paint pictures with words and interpret questions.

I kind of failed on the last part this time, LOL!  

Anywho, replacing the socket itself is extremely cheap and easy and impossible to do wrong (lamp cords are not polarized, so you can't switch the hot and neutral).  It's a great way to make an out of date, barely functional lamp into a useful one - just as in your case here.

Best of luck sir!