I messed with the dremmel and grinder method. It was a real pain in the a$$. I ended up taking them to a friend who works in a machine shop. I gave him the length that I wanted the threaded shank to be, and one of his coworkers machined them down to the precise length. He even chamfered the end of the bolt and properly started the thread. I don't have to worry about crossthreading or mangling the threads on the wheel hub.

It's totally worth it if you know anyone that is a machinist.