I realize your situation, you have it in Post I & II, the 2 machines quote was not for you. There is a lot of programing gone into getting the Mac version, again it won't happen overnight for just you, it is hard enough to get changes in Win version. Is there anyway at all you can pre mixdown the songs in WinBIAB then use another program on the Mac to control them as the conductor does in BB and as the Pedals I suggested b4 that you can program the song parts into and have full control of repeats, looping chorus etc.. There has to be some way of doing it, I bet you will come up with a way !

http://www.codeweavers.com/products/crossover-mac/
http://www.codeweavers.com/compatibility/browse/name/?app_id=274