One option you could do is get TripTunes. It plugs into your antenna and sends a signal to one of two FM stations. One is station 88.3 and the other one I don't remember. Other than that you just have to splice two wires and your all set. I'm happy with the sound quality of it, probably not as good as somehow directly wiring it in, this might be cheaper. I ordered it from Mike at Hilbish Ford. It was $43 for the actual TripTunes. But it also required 2 antenna adapters that were $13 each.
Justin