The eject button on my son's Wii stopped working - apparently a common problem.
Started taking the Wii apart and ran into some Tri-wing screw heads. Why do they bother? Anyway, then I turned to iFixit to purchase the tool for the job. A little more spendy than I wanted, but the tool was of good quality and will live in my toolbox until one of the other buttons goes...
The buttons are surface mount soldered onto the PCB, which is good as you don't have to take the PCB out of the case - you can do it all from above with care.
The spare buttons can be found at mouser.com, part number is 688-SKRTLA (Manufacturer: ALPS #SKRTLAE010)