To my knowledge, it is possible to play mini-dvd backups on a Gamecube after it has been modded. But how exactly does one burn a Gamecube ISO onto a Mini-DVD-R? Is there a mini-dvd burner? Can it be burned using a standard DVD burner?
Just like you would a regular sized DVD-R. Most burners have a second circle where you would put in a mini DVD-R. This is inside the main circle (for regular sized DVD's). It is hard to explain so here is a pic. Source This is a drive for an xbox 360 but is similar to a regular drive found in a PC.