Mike - I think you are flogging a dead horse here - The one finger function is used by the keyboard to trigger the auto-accompaniment. I don't know of any make of keyboard including Yamaha that transmits anything out of midi out other that what is actually played.

If your friend has a TC Helicon there is a mode that can be used where you pre-program the chords beforehand and then use a foot pedal to progressively change these. However - If he uses only one finger chords this may be too much to do all at once.

It's probably best to learn the chords. If you want to play a minor seventh in on finger chord mode he is playing three notes anyway!

Best o luck in your quest.

KF