MIDI is a parameter behavior. You assign the MIDI behavior to a parameter by right-clicking ont he parameter name and selcting MIDI.
It will go into learning mode and watch what key you press (and how hard if it is a velocity-sensitive controller) or controller you adjust. It will then switch modes to respond to changes. You have to activite the auto-record button to record your changes.
All explained in my INSIDE MOTION 2 dvd from Magnet Media (www.digitalmediatraining.com).
Jim Kanter,
Digital Film Institute
http://www.dfilminst.com