It can be done, you have to install tha homebrew browser, find a NES emulator, then download the games from wherever one does that sort of stuff. You must have (unless things have moved on) a Gamecube controller and an SD card in your Wii. if you want more info, i can dig it out for you, just post back, it may take a day or two, but it is relatively easily done.
hope that helps. 👍