I basically agree with the messages above. Don't do this unless you really need to. But if you have to... .....
I got the mirrors apart. It's pretty complicated, and if not very careful, you can damage the plastic clips that hold the 2 halves together. First, remove the mirror from the truck, it is help in place by 3 nuts. Then, you need to take out the mirror piece out of the main assembly. If you adjust the mirror all the way in one direction, you need to remove the clip, mirror and wiring harness. You'll then need to remove the mirror body / assembly before the two plastic halves can be removed. The main body is held in place by a heavy duty ring clip (you will see once you remove the mirror), you need to pry the teeth of the clip with a screw driver to get it off. Once remove the main body, you need to pry one of the halves off (this is where the damage may occur), as the clips are of the plastic male/female type. One of the plastic halves fastens via screws to the internal steel beam. The other is help in place via the locking clip mechanism. If you damage one off the female clip, just epoxy back into place, as this only holds the plastic half in place. Once you pry the one half is off, screws hold the other half to the steel beam.