Hmmm, this is harder than I thought. You take a mouse apart and get to the innards. The idea is that you can somehow get it to see the disk spinning around. However, the sensors come in pairs that face each other. Now with my tech head on, I’d unsolder a couple and make something up as loads of people have done already. However, with my “simple system” restrictions it’s more complicated. I played around with using internal reflection to rotate the sensor path through 90 degrees using a plastic fork. It didn’t work very well to say the least.
Down the road, I’m still stuck with how to use the PS/2 output 2oft away where the server is. Serial protocols are good as they work over a fair distance. With mice etc though you have to send initialization up to the device first, which is why you can’t plug a mouse in once a PC boots up. Basically it just gets harder.
This is why there are CurrentCost meters, custom electronics, X10 & ZigBee systems, WiFi stuff, Arduino boards in the mix: hi-tech custom solutions. More thought required, but I’m not giving up just yet.