You can cut the slot for the tang with a doublecut flat file. It will take you about an hour of filing. The Dremel really isn't up to the job. You will need a drill and a proper size bit because you are going to have to drill a hole. The tang holes go over the REAR trigger guard rivets so you just file the rear rivet flat and punch it out. Install the new rivet temporarily to hold the tang in place, make sure everything fits (the stock) mark the location of the hole you have to drill using the tang as the guide. Looking at the pics I have show that on the rifle I had, the rear trigger guard rivet hole was there in the trigger guard but not through the receiver. That's where you might have to drill. Remove everything, drill the hole, you're done. All you have to do now is assemble.
Then all you need are the rivets, a hammer and a hunk of steel (like a vise) to back up the other side of the rivet. Whack it with a hammer and a punch. Don't want to rivet it?
Use screws.
I used to have a picture post instruction set of how to do the job to a SLR but with the lack of free picture hosting these days it's not on the web. I do still have the pictures though. If you want I can email them to you but you really don't need them.
Just order up the tang and use it as a guide for where and how much to file. Pretty much just file the receiver flat the width of the tang.
I had more trouble installing the screws in the K-Var buttstock. Use the Screws for the STAMPED version, not the ones K-Var sells with the milled stock.
Mike