Nothing that you can plug into the M-Audio. You could pickup a dedicated foot-controller board like the Behringer FCB1010 or the Fender Cyber Foot (as used by Guitarists for their rack effects). There are many others by Roland, Yamaha, ART etc. They often have 1 or 2 foot controllers and several assignable switch pedals (Program Change Etc.). Simply plug the KEyboard into the MIDI in on the Footboard, and use its Merge function, Then send the combined output to your MIDI recorder. If you get a controller without MIDI merging, you'll need 2 MIDI interfaces.
If you really want to go authentic check out the Roland PK-7. It's a 20 note footboard with footswitches (For Rotary speed, brake, etc.) and features an attachable/detachable expression pedal.
