How to make Heated Mirrors, this will vary by mirror. But this is the simple concept you can apply to your application.
Heated Mirror Pad
http://www.ebay.com/itm/261666449412?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
3m Automotive Tape
http://www.amazon.com/3M-38583-Exterior-Attachment-Tape/dp/B00JR4D7AA/ref=sr_1_3?ie=UTF8&qid=1429796376&sr=8-3&keywords=3m+automotive+tape
