What's the problem with the trigger? I had a P99 (cousin of the S&W99) and the trigger was actually pretty nice. It did take a few hundred rounds to break it in though....
Trigger work can be done on these but you basically have to cut springs or replace them with certain Glock springs but these make the guy unreliable. I use to own a P99c with a AS trigger. I thought that had a really nice trigger once the gun went to single action.
You can try http://www.carlwalther.com/. I believe he use to do trigger work on P99's
I would just shoot it till it smooths out. The P99 is basically the same gun and for the first 200 or so rounds the trigger is crappy but it smooths out some after that.