Ken,
If you just want to detect the direction of a light, I'd just get some generic CDS cells, similar to these:
http://search.digikey.com/scripts/Dk...-p9001&x=0&y=0

Take 6 or 8 of them and point them in different directions around your car and connect them to the ADC channels on your PIC. Scan the ADC channels to see which one is sucking up the most light...


steve