Tom,

If you need a third pedal there are two options for a midi sustain footswitch.

Midi solutions sells a midi footswitch controller. There is a fellow named Tom Scarff in Ireland who sells a midi sustain unit. Scott Yee uses a Midi Solutions unit to get a fourth pedal into his Tyros. I use a unit made by this fellow Tom Scarff to get a third footswitch into my PSR3000.

Tomscarff.tripod.com. You can find him there.

Beakybird