You clearly bought the chromebook for the wrong reasons then.
Try this software: http://www.linuxliveusb.com/
Works only on Windows. So make the USB on a windows PC.
This software adds the ISO to the USB and make it boot able.
I haven't bootet a USB on a chromebook before.
But check the bios. There should be an option to choose that you want the USB to boot before the harddrive.