Please don't take my word for it, but i would assume that the GW-8 would accept PK5 pedals. Simply plug a midi cable from the pedal's OUT plug to the GW8 MIDI in. PK5 looks for channel 2 as default, but you can set another channel using the pedal controls. I would check the GW8 manual, as they usually have a dedicated chapter for midi pedals. I have a set of PK5 that I use with my Hammond XK1, but haven't tried it with my s910.