Here's our guide on the process, with pictures:
How to Polish the Rear Half of a 98, 98c, and 98 Pro
Mortisdeum (author of the guide) is a pretty good dude with a Tippmann, he should be good for answers if you have questions.
Of course if you do I encourage you to post them here so that other people can contribute and we'll all learn something.
After the sanding, where he uses the optional toothpaste, I use Mother's aluminum polish or Mag polish I think its called now. Toothpaste works good though, and well...You probably already have that.
