is this the radio you have:
http://www.mp3car.com/vbulletin/newb...rd-fiesta.html
http://www.mp3car.com/vbulletin/car-...-replaced.html
http://www.mp3car.com/vbulletin/car-...500-radio.html
You would probably be better off just getting an aftermarket cd player (cheap check ebay) and hard wiring it into his car.
From the sticky at the head of this forum:
http://www.mp3car.com/vbulletin/car-...questions.html
This forum is dedicated to CarPCs and installing them in your car.
The car audio forum is dedicated to integrating your car audio system with your CarPC.
For specific questions related to car audio equipment systems that do not include CarPCs, I would recomend checking out car audio specific forums:
http://www.elitecaraudio.com
http://www.carsound.com
http://www.caraudioforum.com
http://forum.sounddomain.com
http://www.realcaraudio.com
http://www.carstereo.com
http://www.caraudiomag.com
http://www.termpro.com
http://www.the12volt.com
http://www.talkaudio.co.uk
http://www.caraudiosecurity.com
et. al.
So maybe someone on one of those sites has done what you want to do and has the answer for you. Honestly, it's probably a lot easier to just get an aftermarket radio, you only need a constant 12V, ignition 12V, and a ground (which every car should have) and then you wire each speaker independently to the radio.