Here's how I did mine (on my 03). Antenna (magnetic) is mounted on the back left roof - just above the upper left corner of the rear window. I snake the wire along the left edge of the rear window (there is a lip there I can tuck it into). From the bottom of the window I go into the trunk. I then routed my wire into the cabin through the left-rear seat-belt hole (shoulder belt). I had to take off the seat belt cover (was just a plastic lid). There was a plastic plate I had to drill a hole through, but it's nothing that anyone would ever see. Routed the wire through that hole and by the seat belt (making sure the wire would not get caught up when the seat belt was in use). I followed the back of the rear seat to the molding above the rear door. I tucked it in the molding, across the center pillar, and through the drivers side molding. Down all the way to the unit itself - I have the cradle mounted on the left (above the dash).

It's not something I'd like to do often, but it works and the wire is nicely hidden for most of the route.

*** Retired after 65,000 outstanding miles ***