Dang! I might take a look at that. I made a 12.04 Live-USB for my Macbook 1.2, late 2007. It helped to have a working Live-CD so I could check Linux names for the USB stick, and so on. I used the instructions at ubuntu.com for making a Live-CD, but had to burn the disk 4-5 times before I got one that worked reliably.
I could NOT make a Live-USB following the directions at ubuntu.com. They may work for newer Macbooks, but not mine. I found a link to these instructions. Then I messed around with the grub.cfg
file for days before I got:
# grub.cfg for MB1,2 USB Install F11
# Timeout for menu
timeout=20
default=0
menuentry "UBUNTU USB" {
echo
echo "FAKEBIOS"
fakebios
echo
echo "SET ROOT"
#set prefix=(hd1,2)/boot/grub
#set root=(hd0,1)
set root=(hd1,2)
#set root=(hd1,2)/boot/grub
#echo
#echo "INSMOD"
#insmod (hd1,2)/boot/grub/linux.mod
echo
echo "LINUX"
linux /vmlinuz root=/dev/sdb2 video=efifb agp=off
echo
echo "INITRD"
initrd /initrd.img
echo
echo "IMPLIED BOOT"
}
I found the echos very helpful. It gets all the way up to the implied boot and almost finishs, but failed mounting things on root, like /dev on /root/dev. I played around with the 'root=' arg on the linux command until hit on the one that there. I left a bunch of other stuff in comments. They didn't work for me, but they might for you.
I didn't find much out there. I even found a claim the Macbooks can't boot from a USB stick. I hope this helps.