You're right my mistake, however here is similar list to that but with loopbacks.
Here are a couple examples;
menuentry "Ubuntu Live 9.04 i386" {
loopback loop /boot/iso/ubuntu-9.04-desktop-i386.iso
linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=/boot/iso/ubuntu-9.04-desktop-i386.iso --
initrd (loop)/casper/initrd.gz
}
menuentry "BackTrack 4" {
linux /boot/bt4/boot/vmlinuz BOOT=casper boot=casper nopersistent rw vga=0x317 --
initrd /boot/bt4/boot/initrd.gz
}
menuentry "BackTrack ERR" {
loopback loop /boot/iso/bt4-pre-final.iso
linux (loop)/boot/vmlinuz find_iso/filename=/boot/iso/bt4-pre-final.iso BOOT=casper boot=casper nopersistent rw vga=0x317--
initrd (loop)/boot/initrd.gz
}