Balding_Parrot and pure_hate have each written excellent tutorials on installing BT2 as a live install to an SD card or USB flash stick with "save changes" feature, the same procedures also work for BT3. After following one of them, I then booted BT3 from the liveCD, mounted the flash device, browsed to /boot/syslinux on the device, and edited sylinux.cfg

I realized there was a problem with compiz on the original 7" Eeepc; it runs fine but some config windows are too large for the screen so one has to click alt + doubleclick and drag to view the OK buttons etc, but this doesn't work well with compiz. My first edit of syslinux.cfg was to make a boot menu item which I named Eeepc, it uses the live install and saves changes, but doesn't use compiz

LABEL eeepc
MENU LABEL Eeepc save changes
KERNEL /boot/vmlinuz
APPEND changes=/dev/sda3 vga=0x317 initrd=/boot/initrd.gz ramdisk_size=6666 root=/dev/ram0 rw chexpand=255

Second, I made an entry for other machines to use compiz and to also save/use changes made from other machines

LABEL compiz
MENU LABEL BT3 with Compiz and persistent changes
KERNEL /boot/vmlinuz
APPEND vga=0x317 initrd=/boot/initrd.gz ramdisk_size=6666 root=/dev/ram0 rw chexpand=255 load=cubez autoexec=xconf;cubez;startx changes=/dev/sda3

Note: changes=/dev/sda3 will have to be the correct path to your Changes partition, you may need to edit this. Also, be sure to create a folder titled changes inside the Changes partition if it's not already there

Finally, I kept all the default menu items beneath these two, booted into the flash, and began to enjoy BT3