This project started because another member wanted to exchange his chrome mirror caps for my black ones. I could only find some information about taking off the mirrors from the Muth (signal mirrors) website. I used some of their instructions to shortcut the process a bit so you just remove the mirror caps rather than the entire mirror housing and door panel.
To do this all you need is a T-15 (and maybe a t-10) torx screwdriver and either a flathead scredriver (a pretty large one) or an automotive trim removal too (something good to pry with).
Start by rotating the entire mirror housing and arm, forward...just push on it toward the front of the vehicle. Next, push the bottom of the mirror all the way in, allowing the top of the mirror to stick outside of the mirror caps.
At the base of the mirror insert your prying device (flathead screwdriver), right about the center of the mirror base. In the center is a solid piece that you can use to pry without cracking the mirror or the mirror cap. When you have inserted your prying device, carefully and slowly
push up (rather than down) to slide the mirror itself upward. The mirror will pop free after moving it upward about 1/2 to 3/4 of an inch.
CAUTION - BE CAREFUL NOT TO CRACK THE MIRROR OR THE PLASTIC BORDER AROUND THE MIRROR 
This is the inside of the housing without the mirror:
The next step is to remove the mirror positioner. Using the T-15 torx screwdriver loosen the 4 screws holding the mirror positioner in place. I have circled the locations of the screws that are somewhat hidden from plain view (you may need a flashlight to see them). You may also find that a smaller T-10 screwdriver is a better fit...just don't strip the screws.
After you remove the 4 screws holding the mirror positioner in place, unplug the wiring harness from the back of the positioner. Our 2008 has a single plug that just pulls straight out. The 2007 has 2 plugs that just pull straight out (take note of which position is in which spot).
This is the inside off the housing without the mirror positioner. You will use the same T-15 screwdriver to remove the 4 screws holding the mirror cap to the structural arm. Once the 4 screws are removed, just negotiate the mirror cap upward and off of the structural arm.
Just reverse the process to install the replacement mirror cap.
This process really is pretty quick. We switched out the mirror caps on 2 H3's in about 15 minutes.
Hope you find this helpful!
