personally as I get ready to do biab recordings with my sax playing, I'll be recording using different programs to .wav files, then combine them later in a program like sony vegas or cakewalk sonar... I'd do separate audio outputs, then combine / tweak/reverb/mix them in a software program as a second step.

step 1: output biab to .wav
step 2: play along w/sax over the .wav (playing it to headphones in media player), by listening to biab .wav in headphones, while using a mic clipped to my sax, recording via adobe audition to wav
step 3: combine/layer the biab wav and sax-recording wav in sony vegas or other program