Under ubuntu use /gksu nautilus... But as far as I know, you have to burn your USB instead of copy files, which is done by WinToFlash tool (under windows), means you have to borrow someone's PC for half an hour.
Nothing more to say. Follow the step-by-step tutorial and you are good to go, worked for me. If you have any questions, feel free to ask me in Skype (keksdose112xd).
EDIT ; You will need another PC atleast to configure the USB stick, sorry. Forgot to read that...