I haven't done it on a bike, but in auto and plumbing I've carefully cut the threads in one or more places then taken a cold chisel to it to break it loose. You may then need a shop to chase the threads with the correct die, or use an old freewheel hub (threads are the same on the NDS, I hear).
Or cut a wide slot across the face, and use that for cold chisel purchase at the outside edge of the piece.
Heat (electric heat gun) may help, but you probably just can't get enough torque on the piece.