Here are some pictures that may help with removal and installation. Pictures are of driver and passenger side - procedures are the same.
You
can remove the glass without taking off the mirror housing cover. Angle the mirror such that you can squeeze two fingers behind bottom or top centre of the glass, and apply even pressure to pop the mirror off. Make note of the heater wires in the bottom left of the photo.
Given some delicate plastic bits, I opted to remove the mirror housing cover. Remove two Torx screws on the bottom, and a plastic plug which reveals a hole that lets you manipulate a metal spring clip that holds the cover on. Push the tab on the spring clip towards the back of the car while pulling up on the cover. The cover must pull straight up to clear two mounting posts (visible in the above photo); then you can manipulate it a bit more freely to remove it completely. Harder to describe than it is to do.
A detailed shot of how the mirror lens attaches to the motor ring. There are four such alignment points, with two plastic clips each.
HTH,
fitzski.