I guess that would be a solution.
But it would require a lot of calculations and I would look like Sam Fisher

I'm thinking more of something like the Wii-Bar, which is essentially just like the white spots for the camera. And since I would like to reduce the amount of equipment needed, I will try to get it to work with I guess about 4-6 points.
They could then be mounted on sunglasses, or just white spots on a black paper.

The Wii-Bar contains 10 lights, 5 on each end. I think the way they do it is looking at how much the points a getting closer together. If they all come closer together at the same speed, then they are all getting closer. If the points on one side move closer together faster than on the other, that means this side has moved closer while the other one has moved away, so the player has turned.
Something like that...

But I'm not sure if tracking that many points, with the small resolution of a webcam, is going work out.