There are two distinct issues: booting from USB devices and partitioning USB devices. I believe that if you follow the directions at the end of prep(8), you have a modern BIOS, and it isn't too buggy, you should be able to boot from a FAT file system on a USB device (that is, load a kernel from it). Depending upon your BIOS's treatment of USB boot devices, you may need to use 9load's bios0 device rather than, say, sdC0, and that in turn requires *nobiosload to not be defined in plan9.ini.
I'm talking to nemo about what we should do to partition USB devices.
