not sure about doing it from the chords page but in tracks view you can generate any realdrums you like and cut and paste everything from a single bar to a complete track

and if you 'rough out' a song in BIAB as most of us do, i would think that if you open the BIAB file in RB you should get the drums you chose in BIAB - including part markers for multistyles.

i know RB regenerates BIAB tracks but you can of course drop and drag a BIAB tracks into RB as a wav file.