how to boot from usb if my pc or laptop does not have the option?


http://www.plop.at/en/bootmanager.html
-download zip
-extract it
-burn iso to cd

-boot from cd
-select USB
-press enter
-if you get message "Loading boot sector, waiting for any key to boot. N = continue search", 
press enter to continue booting from usb.

If it does not work, try pressing u, or "shift u", or "ctrl shift u".
as seen here http://forum.plop.at/index.php/topic,34.msg709.html