When I replaced mine, I simply cut the head of the bolt off and put the bolt in from the bottom up. Just to be sure, I used loctite on the nut since I was putting on top.
Steve Brotherton recommended this approach and it worked well. If you have a torch handy it makes this a very quick job, If you don't have a torch, cut it off with one of the small air grinders and a cut off wheel. Be careful to be out of the tangential path that debris would take if the wheel came apart.