I have kindof a unique way of mounting my radar detector and i thought I'd share. Plus this will explain how you can use any house hold telephone wire for power.
(This works for my sti magnum, i cannot guarantee it will work or wont damage your detector)
First off here is a picture of the final product.
The first thing you will need to do is make your power harness. Take your standard telephone cable. Try to use a higher quality cable. The cheap ones are hard to strip cause the wires get really thin. There are 4 wires in most. You only need to use 2 of them. The 2 center pins are used for ground and power. And it is the opposite of what you think. Green is positive 14.4v switched power and red is the negative. This is just how it works out. MOST telephone cables should be similar. Double check the pin locations using the picture of my cable below.
I took this cable and added a spring to it that way i could tuck it away when i dont have the detector up. The reason being i dont use it in the city. I took a standard magnet you can pick up at just about any hardware store and stuck it to glass so i can lay the wire out of sight.
I then attached the "permanent mount" from ebay. I have these in both my cars and love em. They come with 3m tape and just stick onto the windsheild. The 3m tape comes off pretty easy and you can use a razor blade and goo gone to get rid of any residue. (I removed my last one from my old camaro).
Now run your cable inside the front of headliner over to the a pillar and down inside the weather stripping to the fuse panel. Where we will find switched power.