You adjust it with the 3 screws on the front.

Are those scale plans that you have taken the phots of the parts on? I would like to gat a copy of them for sure. Can you email me a copy? I've already got a laser, screws and some plastic. I'm almost good to go. :)

Scans of the blueprints would make you my hero :-D

I am planning something similar, cept I want a Surefire in there. I can't figure out where to put the batteries though. On the Laserex model they route power all the way back to the back grip, and thats the part that requires the shell spliting.

Is there enough room to fit two flashlight batteries in space you open up? A single solid unit for the both bulb and batteries to mount in would be ideal, but I'm not sure whether thats possible heightwise.

My sketch was done to scale so that I could plan out the position of laser assembly and battery housing. I can scan it.
http://www3.sympatico.ca/aftershock/p90lasersketch.JPG
I doubt there is room for larger batteries up front unless you permanently installed rechargeable and only had the connector showing at the surface. There is a wide carriage connected to the trigger assembly which slides forward into that space. You can’t install anything which will interfere with that. Examine the gun diagrams and you will see what I mean.
Another alternative I just thought of would be to route the wires to the main battery at the back and tap in. You might need to check that the lightbulb is appropriate for the voltage you will get from an AEG battery...i.e. might need 9v instead of 6v. Do a test first to see if current draw will dim the thing everytime you pull the trigger.