I made my own for when we were Auto-xing and racing the civic. It's a little ghetto, but was fee to make and worked really really well. We used a tripod piece so we were able to adust the camera up and down, left and right, and swivel it. I could get alot of different angles, from driver shots, to full windshield shots.
For the 996 though, im not sure because you dont have headrests like those in the Civic. I have the same problem in the 944. Something with suction cups would work, but something that connects to the seatbelt retractor bolts would also work.