from what i've found, due to "security" concerns, BB doesn't allow for an audio gateway to be used with any PC interface. Instead i just ended up going with a bluetooth car kit from sony/ericson that i have the audio spliced into my center channel speaker. I just mute/pause my carpc when i get a call.
blackberries suck for this kind of support and i'm probably going to get something new at some point
also you can look here for more info on it Blackberry 8100 Support - MP3Car.com