http://www.nissan-techinfo.com/TSB/TSB_ ... tsbType=AI
This link shows directions for installation of most accessories.
It gives instructions for replacement, not upgrade.
Pry the mirror off, if there are 2 black wires, you are prewired.
I ordered heated mirrors today, only $75, I'll ask at the dealer if they're prewired.
They would go on when you defrost rear window.
I won'tbe able to install for 2-3 weeks.