After creating my OpenWRT live USB (Easy Live USB for x86 OpenWRT), I wanted to use it on an older PC but ran into a problem: its BIOS does not support booting from USB. I had two choices. One was to boot up Linux from CD then switching to USB drive. The other was to get a CD bootloader that can read USB drives. Not wanting to do more work, I went searching and found Plop Boot Manager. It is very impressive. Compact and full of features. It handles multiboot. It works with many bootloaders. It can boot OS on USB or CD without BIOS support. It even has a great GUI reminiscent of video arcade games. And it’s free. Do take a look.
But if you just want to get down to business, I have a ready-to-use CD image (plpbt_hiddenusb.iso on my SkyDrive). Just insert the CD and plug in your USB drive. Plop Boot Manager will do the rest.