I still dont have a clue how you can get it from the roof to the back of the headunit.
If your sitting in your drivers seat, look up, you see the lights. so you feed the cable down to the left hand side till you get to the doorframe, it goes down there ? down to just above the pedals then up to the back of the headunit ? Thats the only way I can work out, and I'll be a jocks auntie if I can workout how to feed that through there.