[themightytimmah]

This guy builds kits for that sort of thing - drop him an e-mail and he could probably build you a custom kit that you could install in 45 minutes or so.

eBay Motors: VALENTINE 1 RADAR LOCATOR " IN REAR VIEW MIRROR" (item 260200561024 end time Jan-13-08 08:00:07 PST)

E-mail is at the bottom of the link, they'll set you up with a mirror install and a custom enclosure, it's an easy install for a local car audio shop.