Trim the iso to a filesize that fits on a single layer DVD, I'd guess.

 

im having a hard time finding my reference; im going to give the old, i've heard this bit, a go ! ;P

use imgburn and burn the disc, i assume its smash x, and let it burn to the edge then stop the process. similar to what Pikachu025 said, wiiscrubber has been used to bring the iso down to size