I realize this is a subset of an earlier feature request (#3406699), but would also take significantly less work to implement methinks. Especially because I've included a (half-finished) patch.
I hacked this up nearly a year ago, but never successfully managed to update the UI other than the graph. Midi CCs 20-28 (inclusive) control the Hammond organ drawbars. If someone could get this to the point where it updates the UI, I'd be super-happy.
Also this is against revision 3fa2934d35d96a1268ca91525ef71bfcd52490e1... sorry.... like I said this was hacked together a long time ago. I went out and got a Nord Stage 2 last June so I haven't really needed CALF...