I've just done a bit more reading.. would it be possible to have a couple of bright IR Leds on each shoulder and a wii camera in the bots head ? My idea being that the camera would pick up the ir light as a reflection off the object and centralise it's position (turn it's head towards it) ?
Is the wii camera that sensitive it would work ? Has anyone played with it yet ?
I saw a guy using two power LEDs for projecting two IR spots (replacing the IR bar) onto a wall where he used a projector for playing a Wii directly off the wall, It was a white, fairly reflective wall though, but all it comes down to is power vs. reflectivity to IR and well, how much you're willing to pay
Roitner (Germany) has got both high power narrow beam (4°) IR LEDs and IR LASERs, although the latter is way too dangerous to use like you intend (almost instant blindness if you look at it) and even a high power LED needs extreme caution, as the eye don't see it, hence the closing reflex is null and void to IR.
I'm not sure what you wanna do - shine the LED's somewhere (position determined by what?) and then getting the Wii-Mote to track it - seems a bit pointless to me, as whatever determines where the IR shines it already knows where, so no tracking is needed as I see it.