need help with Oberheim Minigrand

I purchased a Minigrand on eBay and it did not include a manual.
It is currently configured to respond to a sustain pedal plugged
into the back of the unit.  Can anyone tell me how to configure
it to respond to the sustain pedal on my MIDI master controller.
I'm using a combination of Yamaha KX88, KX76, and Fatar SL760.
Any help would be appreciated.