julian are you talking about the Electric ICE RGB Trackball Lighting Upgrade Kit ? Do you just slice it to the 12 v line on your power supply ?
Yes that's the beastie!!....and Nope, You splice it to the 5V Line and the other connections on it to ground. It has the correct resistors built in.
It has 4 leads...
1) +5V (attach to PC 5V Line)
2) Red Ground (attaches to pc ground- black lead on PC Supply)
3) Green Ground (attaches to pc ground)
4) Blue Ground (attaches to pc ground)
If you attach each ground via a 100 Ohm trim pot, then you can dial in any colour or light intensity that you want. Easy Peasy!!
Best Regards,
Julian (Fozzy The Bear)