For the backups to work he is going to need a cios as well as a couple other ios's. The easiest and safest way to set your wii up for this is modmii.
To use the letterbomb hack you need to know the mac address of the wii you are trying to run unsigned code on. Have him go to settings >> Internet >> Console information. Have him send you this with his system version (also in settings)
Then once you have that run modmii, answer all the questions with the info you have and it will generate a set of files and a step by step guide to install/configure it on the wii.
You drag the files to the Wii's SD card, follow the guide and you're set. Easy, take about 30 mins. It will get the wii configured to run all homebrew, as well as legal backups. (Really buy games, support developers, you can rip games directly on the wii to the hard drive, it makes it super easy.)
After you make the files/guide modmii can even download emulators and homebrew and have it work instantly when you put the files on the wii. The wii has some really great SNES, GBA, NES, Genesis emulators with good speed and really polished interfaces.
So follow modmii, with it the Wii is easiest console I've ever made to run unsigned code.