LED 3mm , color of you choice
Solder and 15watt soldering iron
Resistor (if you want)
Tir-wing screw driver
About an inch of wire
And thats about it
Heres what the final product will look like :)
Also you can get everything else form Radio Shack.
Here is my youtube video of it in action http://uk.youtube.com/watch?v=9M6cHJIr65k
Step 1: Lets get that wiimote apart and the B button ready for the LED
Then solder wire to the LED ends, make the wire about 1 1/2 inches long. Insert your LED into the B button. You can either remove the far bottom clip like i did or just put it by the clip.(what i did was once i removed the clip i took my solder iron and poked a hole threw the tube) picture #2 is where you remove the clip. NOTE: the positive (+) leg of the LED is the smaller piece of metal if you look into the clear part of the LED and the negative (-) is the other one.
Picture #3 is where you melt (optional) a hole threw the tube on the button. If you did this step, all you do is melt a hole about in the middle of the tube until you can fully insert your LED. Make sure not to melt the top of the tube because if you do it will be really hard to put the button back together and have it feel smooth.