I hooked mine both up to the 5V molex connector located in the backbox, so that they are both illuminated at all times.

You need to first open each light cycle up and then solder one wire to positive end and another one to the negative end. You'll also need to make sure to either superglue down each button on top of the light cycle so that it is always depressed, or melt it down - either way works but supergluing seems to achieve a much cleaner and nicer looking result.

In terms of feeding the wires, for the blue light cycle I fed it down through the playfield to the right of the recognizer where there are already some wires present. As for Clu's light cycle, I actually have that running all the way to the right and then around the back of the playfield, instead of feeding it down somewhere. It's quite easy to do and the result doesn't look as bad as I thought it would. Can barely see it actually.

You'll have to experiment with the molex connector a little bit to discover where the ground is; can't remember exactly how I wired it but I can check when I get home.

Someone also wrote up a guide which is somewhat useful (but confused me a little bit when I was trying to follow it. It hooks up the two light cycles together in a hub, which I didn't do).

http://www.cnypinballpleasure.com/tron.html

_{Post edited by Mateui}

I had that problem to so what I ended up doing was taking the soldering iron and melting the button down, pressing the melted plastic downwards and letting it cool off so that the switch is always depressed.