No special tool, same 8 mm Allen key. Was he turning the wrench the right direction? I always get turned around removing the pedals that wrench from the inside of the crankarm, since you're actually "tightening" (pushing the spindle through, away from your hand) to loosen, and "loosening" (pulling the spindle toward your hand) to tighten. Combine that with the fact that of course the right pedal is right hand threaded, left pedal is left hand threaded, and I practically need a mirror to figure out which way to turn the stupid thing.