yeah you would need a electronic throttle pedal from a mk4 and also whatevers involved in wiring it in. would be a major headache I'd imagine, I fitted the mk4 pedal in my mk3 with an aum which is already electronic throttle and that was hard enough!
had to make up a custom bracket to mount the pedal and remove the old pedal which involved taking out pretty much all the dash as the bar runs along through the centre console to the passenger side
Also not sure whats involved in wiring in the pedal but i think you would need to wire it into the ecu as well as the wiring from the throttle body to the pedal