If you haven't got around to the real band app yet it might be worth taking a look, you can actually do that in it.
You can do it in biab but you have to Save track as Performance File first, Audio - Move Performance Track to Audio , Window - Audio Edit, snap, copy and paste any relative section from the track to bar 0.
If you have more than one track use Audio - Move Audio to Performance Track, then do the next.
You can also do it in real band then bring it back into biab
http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=343721There is also a usertrack request for that
Intro starts on this bar (2 or 3 bar intro/count-in/lead-in/pickup for bars -1 & 0,1).
Hope this might help.