I'm pretty sure that if you're doing a SD dump from your wii, you need an adapter that fits into the GC memory card slot. It's a way to get an ISO of the game without ripping it on the computer. If you ask me, it's probablly safer to rip it to your computer first, you don't know what kind of update it has that may brick the wii [never ripped via SD, so I'm not sure if that's an issue]
start SDload (or whatever dol loading method you want to use) then start an SD dumper program. It will ask you to insert a disc you want to dump and then the SD card you want to dump it to (the SD card needs to be inserted in an SDgecko; http://ngc.scorpei.com/GUIDE-SD_adapter.html). --> No update done because the disc is never in your Wii while the wii is in Wii mode.