How can I hard wire a radar detector?

[phiebert]

I just got my V1 detector and I want to hard wire it to an "ignition on" fuse in the fuse box. Has anyone gone through this and figured out the easiest way of getting the wire from the fuse box up to windshield without a lot of work (ie taking the dash off)? Can I come out a defrost vent or do I need to go around the edge or...?

I don't want to tap into the rear view mirror wire because that is always on and I've already killed one battery leaving my detector on!