Supposing the device is formatted as ext2, not FAT...
I use grub4dos with a menu.lst entry as shown below with the kernel, initrd and tce directory all stored under /boot/core4.7.7 You'd have to tweak it to reflect your own directory layout, filesystem label, etc. Once you boot to the CLI, you can use tce-load to download the GUI and whatever apps and such you want.
# 2013-05-21 4.7.7
title Core 4.7.7
find --set-root /boot/grub/menu.lst
kernel /boot/core4.7.7/vmlinuz quiet tce=LABEL=my_fs_label/boot/core4.7.7/tce waitusb=30:LABEL=my_fs_label
initrd /boot/core4.7.7/core.gz