For YEARS now I have been looking for a way to boot from USB on a computer that does not natively support it. I've asked in Linux, Windows, Hardware chatrooms, with no luck. Everyone said it was impossible, something about requiring a kernel to host the USB drivers that would be needed, which would preclude loading the target OS kernel...
So yesterday someone is talking to someone else and makes a passing reference to PLoP for booting from USB on computers with a BIOS that doesn't support USB boot.
http://www.plop.at/en/ploplinux.html
AND IT WORKS!!! I am now very happy.