Robert Messier demonstrate dhow to do this on version 4 today at the UK roadshow.

he played the bass line to Billy Jean using the built in metronome as a guide for tempo. Then added the Billy Jean chords, ripped the first two bars of the audio drums from the original music track and added that to the style (although he had done this part previously)..within minutes he had made a new style that was very authentic sounding.

So yes..its possible