Here is a video where I show the whole job:
http://www.youtube.com/watch?v=uu4QQPrxIQM
I just did another one of these jobs today and it came out perfect with no damage...the key with the plastic type is in how you work the drill...you need to very slightly angle it and drill very slowly so the bottom part of the rivet just sort of falls apart and then you can pull the top part off.
I personally have not tried re-using the mica after cutting but personally I prefer to just remove all traces of it and use external caps, that way you never have to open that can again in case some other trouble might come up with the caps. Sometimes in addition to the silver migration I think intermittent contacts between the contact fingers and the mica sheet may come in to play.
When I was younger I too tore apart many radios in frustration trying to get them to work due to the IF can cap problem and getting no sound after fixing all the other problems I knew about (bad electrolytics, paper caps, etc). By the time I got to college I figured out what the problem was but ended up scavenging working IF cans from junk radios, not being brave enough to open up the cans and tackle the problem directly.