Most webcams can be easily modified to use infra-red, like the wiimotes.

There is a small glass filter inside of most webcams, this can be replaced by a filter like on the end of a TV remote control.

Not only would the modification allow the camera to detect infra-red light, but it would also prevent visible light from entering, thus replicating the sensor on the front of the Wiimote.

I tried the mod to an old digital camera, but got sloppy and it broke after working for a short while. Never take experimental projects to school with you.