I haven't done it personally, but have looked around since i probably will need to if I get tow mirrors.
I found an Ehow link
If you got manual windows like me, you need to get a C clip puller tool to pull a pin out from between the crank and the door.
I have heard that the panel clips around the sides of the door can be pulled off using a putty knife, but they recommend a panel clip puller tool
Sorry for the limited info, but this is all i have.