Not sure about the construct of your particular mirror, but I have removed the glass/mirror in several in the past, by carefully prying the rubber sealing ring that holds it in the frame. You have to get under the glass with a small knife blade, or something similar, and work the glass out from the rubber which retains it. I have broken glass in the past, trying to do this with seals that were not really rubbery, but rather a hard plastic, which maybe would soften with a heat gun - but also would maybe melt.
![Sad :(](http://forums.sohc4.net/Smileys/default/sad.gif)
At any rate, once the glass is out, most mirrors I've seen have a nut holding the frame onto the ball of the stem, along with a spring arrangement that allows it to pivot. These can be disassembled.