The current modchips available for the Wii console only act as a bypass for the Wii's disc drive protection - preventing any back-up discs it detects from booting on the console.
According to a recent video posted on youtube you can achieve the same effect with a parallel port cable soldered to the drive board and then run the backup games via a PC.
Textb00k: (the video author)
You will need a male parallel port and a couple diodes, both parts available at Radioshack for under 3 bucks. Follow Erant's instructions on soldering in the cable, then use Syndicate or WAB's "ISO Loader" or "WABModCheap" programs to temporarily patch the drive firwmare to allow backups to load. Not as feasabile as a modchip for the reason that you have to use a PC every time, but for 3 bucks and the chance to get it done right then, it was worth it for me.