Voice chat routing in Steam for Mac games

In the Valve games (Left 4 dead, TF2, etc), I can either route all the sound through my speakers (which makes voice chat weird) or through the earpiece on my headset (which makes the in game sound effects sound crap).

Is there a way to route only the voice chat through the earpiece, and the rest of the sound through my speakers?

I'm running OSX Lion and the headset is one of the new PS3 bluetooth headsets.

Looks like the only way to do this is to use a third party chat application that lets you explicitly specify the input/output devices instead of using the OSX configured ones. Ventrillo seems to do it but as Ventrillo for Mac sucks rather badly I'd prefer to find a better solution.