I'm not sure either, i wanted to save my game automatically on my SD card, which i don't think you can do.
All you can do is, go to the Wii option and go to "Data Management" (I think that's what it's called), there you can be able to save your saved files or channels onto your SD card.
The only thing you can do is transfer files from Wii's internal memory to SD card, don't think there's any way from game disks to SD card.