My wife and inlaws have come up with a project for me to do.  Some friends of theirs cut some wood (They own a tree trimming service so they saved some from a job which has now become endeared to them...) which they intend to use as centerpieces for a large gathering--it somehow must be exactly these pieces of wood.  OK, fair enough.  However these need to be treated so they look nice and also so they don't split.  I don't have a kiln to dry it myself or would have done that already.  I am told one thing to do is treat it with Pentacryl, which is out of stock locally.  I might order some but I was wondering if there are any similar products which you guys might recommend that could be in stock for me to pick up.  What do you guys do?

Is the wood cut into lumber, left in rounds?  What is it going to be made into?

In rounds, each round will be used as a pedestal.

It's gonna split

You can coat the end grain with Anchorseal, paraffin, or latex paint to prevent rapid drying and the resultant cracking, but that needs to be done right away to prevent cracks. You can also spray them with water and cover them with a tarp to prevent cracks. Anything to prevent rapid drying.

Bottom line, they have probably already cracked,  I've seen rounds develop cracks after drying overnight.

You can soak wood in polyethlene glycol to avoid cracks.
http://www.rockler.com/polyethylene-glycol-peg-green-wood-stabilizer

How thick are these sections?

Pentacryl is expensive, do they plan on keeping the wood forever?  I get it from Rockler.

Pentacryl DOES work very well. I've used it on log slice end table tops about 2" thick. I soaked some green slices for a few days, and they haven't cracked, warped or split in the 2 years since I did it. The bark didn't even fall off. I've even used it on log slice drink coasters with perfect results. These are only about 1/2" thick and they stayed flat with no splits

If it is just for the one event, you do fresh end cuts on them right before the event and they will be fine for a few weeks

PEG works VERY well.

Pentacryl is almost half solvent.

Pentacryl is fine for small pieces of green wood, like for bowl blanks.   for PEG The wood has to be submerged in it for some time, and the temperature of the solution is supposed to stay in a relatively small range so it can infuse into the wood.  

It sounds like you will be working with larger boards.  Edit - you really didn't mention.   What form they are is a big deal.    Air drying will be your best and most economical method.  But it is time cOnsuming  or slow.  You should coat the ends of the planks with a paraffin based paint or even a cheap latex paint will do.  The purpose is to slow down the amount of moisture that can escape from end grain.
Then stack the boards with "stickers" in between boards.  I use 3/4" x 1" x 12" plywood strips as stickers or spacers.  Never had a problem with sticker stain - that is more prevalent on maple I think.   Stack the boards and put a lot of weight on top.   A spot with good airflow is best, to keep it from getting rain on it or blown into the pile.   Stack it on a couple rows of cinder blocks too, well off the ground.

If they can't wait a year or two - the rule of thumb is about 1 year per inch thick to get it to a useable dryness level.   And for those who say it must be kiln dried to 5% moisture content - how did master craftsmen in the early 19th century and before make and nice furniture, many pieces which still survive to this day?   Air drying where I am in western Pa can get to 8-10%.  I have cut lots of boards with my Alaskan sawmill and Stihl 66, and recently got myself a Norwood Bandsaw mill.  I have air dried everything, mostly in my garage.
American Woodworker had an article about building a dehumidifier kiln using a box made of homosote and used a lamp bulb for heat and a household dehumidifier to pull the moist air out.   You could put it in you garage or basement .  That could probably cut your wait time down to a couple months at most.  There are also plans out there for solar kilns - Fine Woodworking had an article way back in their early issues

If these are slices, then time is of the essence- you better get them in PEG soaking that stuff in quickly before they check or split.

PEG replaces the moisture. Used for green turning.