Hey as far as I was aware, the feature is kind of gimmicky. first of all, head tracking is available only in cockpit view, which means only on premiums, which is only 20% of the total car list. second, head tracking cannot be used during a normal race as according to Kaz, the ps3 doesn't have enough power to currently render everything on the track we have so far and still have enough space for a full view
although if you still want to do it, the only tool you actually need is the playstation eye camera. It wont work with the ps2 eyetoy. After plugging the camera in, it can be calibrated in the options menu under the hardware section. I hope this helps you in your decision.