Hey man, check out this company. I am probably going to go this route as the next best option gets pretty pricey (Alpine video/dvd link and iopd control). Here is the website for the company.
http://www.vaistech.com/home.html
I was refered to a shop by a good friend (extrem audiofile) and they quoted me about 800 bucks or so for the parts and instal.
Good luck.
Tom