To use RapidComposer in VST mode with Biab or Realband you just need IL MiniHost
http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=368498

Midi can be dragged directly out of Biab into RapidComposer VST track, RapidComposer VST will have the same chords or your modified ones, once you import the BB Chord Output track from Biab host.
It can re-voice the midi track from Biab.