This should answer your question and help you out:
http://www.reverendbiker.com/
If the link doesn't take you to the Mirror Install page, click on Frontier and then Modifications and then choose Autodimming Mirror from the list. I have his web page bookmarked because it contains a ton of really useful information! Also, all these mod are being done on a LE KC Model, so they should fit your needs to a T!