Removing the mirrors is pretty easy. Scary to just quickly pull up on them to un-snap them from the body but that is in fact how you do it.
See these videos:
http://www.spyderlovers.com/forums/media.php?do=details&mid=247
http://www.spyderlovers.com/forums/media.php?do=details&mid=237
The bottom front snap can be a pain to get snapped back on. I had to do it a few times to get it to snap.
You will see in the first video Lamonster had a little problem getting it snapped back on too.
Now to feed the wire you have to take off the top and bottom front panels of the mirror and unscrew the light bulb fixture (4 screws). It's not as hard as it looks but prying with a screw driver to un-snap them might scare a few people! I was a little leery to do it but just went for it. Once you have the bulb unit out, you will see the pass-through hole under it. Plenty of clearance for a wire.
See this post here:
http://www.spyderlovers.com/forums/...irror-housings&p=475127&viewfull=1#post475127
Only comment is breaking off the snap tabs that look like 1/2 arrow heads. I had no issue with them breaking while taking it apart. However when you go to snap it back together, MAKE SURE you have all of them aligned in the slots before trying to snap one in place! This I think is what breaks them. I almost made that mistake and almost broke one off because I missed getting one aligned.
Needless to say, if you ever burn out a light in one, you will need to do this take apart anyway or spend more bucks to have ti serviced.
Now, you might be able to fish a string or something by playing around with it. I tried a little and gave up hoping to find the hole and getting it behind the mirror. You might get lucky.
Also here is a post talking about other ways to do it without taking them apart. But you do need to drill a hole. See page 2.
http://www.spyderlovers.com/forums/...rror-Arrow-Lights/page2&highlight=turn+signal
Bob