The NES roms are stored in a similar way; you can convert them to GCM images just like with the N64 ones. However, I don't know of any tool able to extract the NES roms from those images. But, you can do it yourself with a hex editor. On the original CE disc, Zelda 1 is located at offset 19A749E0 and ends at 19A949EF (20010 in length). Zelda 2 is located at offset 19C148E0 and ends at 19C548EF (40010 in length). The on-disc NES ROM data is very similar to a ROM dump of the original cartridges and the size matches perfectly, so it was pretty easy to find where the data was at. This technique seems like it can be extended to work with some other games with NES data (the bytes to look for are 4E 45 53 1A, the first four bytes of any NES-NTSC rom dump; the endpoint is usually where it would be in the actual NES romdump). Based on my own tests, this is probably not true, as the data appears to be stored differently in other games (such as Animal Crossing and Metroid Prime).