Yeah it's just burning an image to a blank DVD.
The trouble with some of the scene releases is that they have to be 'unscrambled' before burning.
Once you have an unscrambled image you can burn with any image file compatible burning program. NERO or IMGburn would be fine.
**edit**
Whoops, thought you were talking about Wii games. I must of forgot the topic title.
Anyway it seems just using good media is the key, as long as your burner does a good job on it. You can use full size (12cm) media for GC games.