We need to modify our Wii Sensor Bar for the same reason that we're making an IR Repeater: the Wii is in a cabinet and I want to use ethernet cables for accessories.
I had read that the wires inside were lacquer-coated but I didn't know much more. The wires are stranded and appear to have some nylon running with them. I separated the wires, cut off excess nylon, and then soldered to Cat 5 cable that I put ends on to plug into the wall. I chose to use solid blue (pin 4) to connect to the copper colored wire in the Sensor Bar and solid brown (pin 8) to connect to the red-tinted wire in the Sensor Bar.
The cables are now ready for testing with the Wii. The resistance checks out and there don't appear to be any shorts so I don't expect trouble but I can't test on the Wii until tomorrow.