Now pull the wires up from the door and out a little bit so you have some room to work with them.
Unplug the connector and push the big washer out from the hole:
I have no clue how BMW got that washer over the connector onto the mirror, and I couldn't figure out how to get it off without cutting the wire.... so I did.
Snip off the end of the wire going to the mirror and save it (makes it easier to connect the new mirrors) and just throw away the washer if you want. haha, it's not necessary, the outside waterproofing rubber keeps the water out.
Now, examine the pieces that came with your new mirrors. You should have a mounting plate and the mirror itself.
Take note to how the mirror will fit onto the mounting plate.
Remember that piece of weatherproofing rubber that fell off the old mirror? That goes between your new mounting plate and the car. Here's the order for mounting on the car: The mirror, new mounting plate, weatherstripping rubber, and door.
Now, this step might not apply to everyone. When I got my new mounting plate, the three pegs that you connect it to the door with were too long, so when I held it against the door, it looked like this:
See? Not flush at all, but sticking out. How to fix this? Either dremel down the peg length or use my technique of sandpaper. The pegs aren't threaded yet so its not a problem at all to size them down.
Now it's time to mount the faceplate to the mirror. Simply stick it on, and screw in the 3 small screws into the holes. It should line up perfectly for you.
And when it's mounted: Notice the sanded down pegs and where the screw holes are:
Now you need to make the waterproofing rubber fit onto your new mount plate. I couldn't get the wire and connector through the small hole for it, so I used scissors to open it up a tad:
Now stick the wire through and you're set.