You need something like this:
http://www.harborfreight.com/cylinder-leak-down-tester-94190.html
And then..read something like this: http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/index.html
I'm matt. Im a lurk.
(Ok, Im a friend of robbie's (d. davaine) and other robbie (living4surf), as well as several other people that frequent this site. That's about the best explanation I can give.)