Hello Bill,
AFAIK you cannot boot a CDROM-image from a pendrive. However you might have a look at images/README:
"The diskboot.img file is a VFAT filesystem image that can be written to a USB pendrive or other bootable media larger than a floppy. Note that booting via USB is dependent on your BIOS supporting this. It should be written to the device using dd."
Regards, Andreas Rogge