Add this to your menu.lst:
Code: Select all
find --set-root --ignore-floppies /path/to/file.iso
map /path/to/file.iso (hd32)
map --hook
root (hd32)
chainloader (hd32)
boot
EDIT:
Just read the thread you linked.
1) Install GRUB4DOS to the USB
2) Create/edit menu.lst in the root(?) of the drive with the above code
3) Set boot flag.
4) Reboot and start from the USB.