THe drawbars can be operated manually with an outboard device such as a JLCooper "Fadermaster" or the Peavey 16 ch CC box(NOT the name)
For everyday ease of use - you'd want to write custom drwbar settings into patches and change them from the keyboards buttons. I used it the other night with a live drummer, and was not able to take my left hand off the keys(I play manual bass lines)so working thje leslie F/S was a little tricky, but I had the laptop sitting right over the pitch bend wheel on my keyboard. I was able to "sneak" my pinky up and hit the mouse button to trigger the effect. It was pretty cool, but much easier to use with the arranger on - frees up my left hand a little.
***Also - the Guiter Center is selling that item for $150 or less, so don't order direct!