Good point.
Kewltoy, you probably already know how to build a shock with no rebound, but to save you a search if you dont...
When you are putting the cap on the shocks, you want to fully compress the shaft up into the shock. Oil will bleed out of the bleed hole in the cap (facing up) as you tighten it down, hold the shaft all the way in as you get it to as tight as you want it.
When your done the shock shaft should not extend back out of the body, or a miniscule amout if any. You want all shocks to have the exact same amount of extension (best none, but 1mm ok) when your done.

Enjoy