I've modified the sensor bar in two Wii "installations". In my own home, the sensor bar needed to be routed further than the cable would reach, and it had to go through a tightly packed conduit. For this, I cut the wire to the sensor bar and put a male 1/8" plug on the sensor bar side, and a 1/8" socket on the Wii side. Then I built what is essentially an extension cable out of CAT5 that was already running in the conduit to carry IR signals (on another pair in the bundle).
The KEY to making extension cables is to realize that the strands of copper wire in the sensor bar's wire are NOT bare copper. Each of these tiny strands is insulated with a thin coating, very similar to the wire used to wrap electric motor armatures. When you strip the wire and you find what looks like bare copper, lay it out on a work bench and very gently rub over them (in one direction only) with fine sand paper to remove this coating. THEN you can solder to it with conventional wire.
In the second installation, I was putting in a custom projector screen and built a custom "sensor bar" directly into the frame of the screen. This was built using 2 high output IR (infrared) LEDs from radio shack (part number 276-143). These were connected in series and routed through Cat5 to a neighboring wiring closet which housed all of the equipment feeding this room. The LEDs were then powered off of a 5V DC adapter with a suitably sized ceramic (10 watt rating) resistor in series. The resistor was sized to put 100mA through the diodes. I don't remember the exact size.. but if anything in this paragraph makes sense to you it should be easy to figure out. If it doesn't... don't play with electricity
-Russ
