Grub2

kali linux in grub2

Store iso on standard partition.

menuentry "Kali Linux" {
   iso="/iso/kali-linux-1.0.8-amd64.iso"
   bootoptions="findiso=$iso boot=live noconfig=sudo username=root hostname=kali quiet splash"
   search --set -f $iso
   loopback loop $iso
   linux (loop)/live/vmlinuz $bootoptions
   initrd (loop)/live/initrd.img
}

kali linux grub2 efi boot

Content of /etc/grub.2/40_custom of fedora 21 machine.

# Install grub2-efi-modules to make loopback work.
# Copy file to this location /boot/efi/EFI/fedora/x86_64-efi/loopback.mod
menuentry "Kali Linux" {
   insmod loopback
   iso="/iso/kali-linux-1.0.8-amd64.iso"
   bootoptions="findiso=$iso boot=live noconfig=sudo username=root hostname=kali quiet splash"
   search --set -f $iso
   loopback loop $iso
   linuxefi (loop)/live/vmlinuz $bootoptions
   initrdefi (loop)/live/initrd.img
}