The adjustment tool is a tiny Allen wrench. I don't know the size, but it's the same size as the one included with the Surefire helmet light.
IIRC, there should be a place for it under the battery cover, so you might be able to find it in there if you haven't looked yet.
The other adjustment is on the side, "above" the attachment bracket screw.
I use the IR version, and it's decent enough though it's certainly not the perfect piece of kit. What it is is small, simple, and unobtrusive, and perhaps most importantly, cheap, compared to other IR lasers, and I haven't had a problem with zero loss.
Just watch the switches as they're fairly easy to accidentally depress, and potentially to break (though I haven't done it myself). Mounting a small pistol light "on top" of it does a good job of protecting it.
The other big problem I suspect you'll have if mounting it on a pistol would be finding a holster to fit it, with or without a light.
~Augee