Try this stuff:
Walther Heat Shrink Dermagrip (scroll down to nearly the bottom of the page)
Pic with part numbers
It just slips on then you hit it with a heat gun and it shrinks to fit. It is very grippy and durable. I am surprised that it is relatively unknown as an alternative to stippling or skateboard tape, but it works really well. I had it on a USP45 and have it for my HK45C (traded the USP and some other gear for it), but haven't had a chance to install it yet. It works great on my P99 and G19.
The link I provided is Earl's, who is pretty well known for Walther stuff and is the only place I know of to buy it. For $25, you aren't risking much if you don't like it since you just cut it off with a razor blade and no damage or adhesive, etc.