I made some progress today - it looks like the majority of the components used in the PixArt hookup here:

http://www.kako.com/neta/2007-001/2007-001.html

Are for creating a clean 25Mhz clock signal from a bare crystal. If I buy a crystal oscillator, in place of a bare crystal, then I don’t have to worry about any of that stuff, I can just plug the output from the oscillator straight into the sensor.

I have to film the laser harp for MakeTV this weekend so I have to wait until that’s complete before trashing the WiiMote to get the camera out…