Another option that some people could use if the BIOS does not support USB boot up is PloP. PloP is a USB boot CD, which allows a USB to be booted even on a system that the BIOS does not allow for booting from USB. This can be found on PenDriveLinux.com.
http://www.pendrivelinux.com/category/usb-boot-cds/

Another idea is to use the multiboot tool from PenDriveLinux.com to host all of the above rescue disks on one USB drive. I have not tried this yet, but it would certainly come in handy if it worked.