Wiring diagram is on page 8-15 in the Shop Manual for 99-00, I know that some colors might have changed but you should intercept the ground (front-blk/wht tracer) (rear-wht/blk tracer) and that should do it. that is how I have my lights kill switch set up. Is a lot cheaper to use a two pole switch to kill the ground than to mess with 12v in case the wire comes loose or the switch dies.
Here's what I was able to trace with the diagram.
Working from battery to headlight. Battery is direct wired to starter relay, from starter relay a red wire sends power to fuse 6 (fan) and to ignition switch. The ignition switch in ON position sends power to orange wire. The orange wire runs to a harness connector and to fuse 5 (signal). At the connector the orange wire changes to orange/red which loops back to connector and becomes yellow/white. The yellow/white wire carries power to the headlight dimmer switch and to fuse 2 (headlight LO). At fuse 2 the yellow/white wire becomes white and carries power to the LO beam. The headlight dimmer switch in the LO position connects to a white wire that terminates at a connector. The headlight dimmer switch in the HI position it connects to a yellow wire. The yellow wire runs to fuse 1 (headlight HI) and remains yellow, carrying power to the HI beam and the HI beam indicator on speedo. Black/white wire is ground.
Working from battery to tail light. Battery is direct wired to starter relay, from starter relay a red wire sends power to fuse 6 (fan) and through a harness connector to the ignition switch. The ignition switch in on position sends power to a brown wire and through the connector. From the connector a brown wire carries power to the running lights, tag light and to the "position light" connector in front (not used on US models). Black/white is ground. White/black is switched hot from brake levers.
