[maxmsp] accessing phototransistors on the mac book.

Hi.  I am wondering if and how I can use Max to access the transistor's in my mac book.  I'd like to be able to access the data in the same way that the SMS patch access the accelerometer in the mac book.  I'm hoping that I can figure it out on my own by peering into the workings of the SMS patch but if there are any Max masters out there who have any interesting thoughts on the subject pleas let me know.