Several ways to do this, I'll describe one...

On the Soloist track (assuming nothing is already there), change the track type to Multi using the Soloist|Track Type menu. Using the Piano Roll editor, select channel 10 (drums) using the Chan dropdown box. Enter the note(s) where you want them by holding Ctrl Shift and clicking the mouse at the desired note and beat. You may read up a little on using the Piano Roll editor as there are plenty of options such as adjusting volume, duration, cut/past etc.

Remember that channel 10 is for drums only. Other parts may be entered in the Soloist track by the same method using other channels and instruments. Try to stay away from using 1-8 as BIAB uses those also. Channels 11-16 should be fine.

R