Don't know if this will be of any help but you can see my T5 installation and modification of the tranny cover plate in my gallery at:
http://community.webshots.com/user/Fla54Chevy3100 I used the stock S10 boot and would suggest you leave adequate room above the shifter to be able to remove it without tearing out your sound/carpet stuff. I know the s10 boot is a bit big but "easy access" was more important to me. The sm420 "hole" was simply covered with light gauge sheet metal. Your application may be different but you may get an idea from my application. Just my $.02, hope it helps.
