I just hardwired my passport 8500i X50 with a Safe-n-Sound Mirror Stealth Cord:
Escort Stealth Mirror Cord - "Be Safe with Safe-N-Sound1.com"
It plugs into the power plug for the rearview mirror and takes all of about 7 minutes to complete. It's so easy, a DIY writeup would just be silly.
The cord cost me under $10 shipped and got to me within two days via USPS. Couldn't be happier.