I have Ubuntu with grub2 installed in an Apple Macbook pro with dual boot (using rEFIt), and I would like to use grub2 to boot the LiveCD ISO image of a system based in Debian too (CrunchBang). The ISO image is saved in the same hard disk, same partition as Ubuntu.

I can easily boot many other LiveCD ISO images, but I cannot boot this one, and I cannot boot the MacOS system, from the grub menu, either. The installation of Ubuntu left a couple of menu entries to boot MacOS, but they never worked. SO I don't know if it is possible to boot them, and how.

I have tried many options, but the menuentry I am trying now to boot crunchBang is this one:

menuentry "crunchbang-10-20120207-i386.iso" {
   set isofile="/home/user/Desktop/ISO/crunchbang-10-20120207-i386.iso"
   loopback loop (hd0,3)$isofile
   linux (loop)/live/vmlinuz1 iso-scan/filename=$isofile toram=filesystem.squashfs findiso=$isofile boot=live config --
   initrd (loop)/live/initrd1.img
}

And I copied it from here: http://linux4netbook.blogspot.com.es/2012/08/due-crunchbang-e-un-pennino.html