Exactly. I want to put a Live-CD like partition on the drive to boot off of. Something like Knoppix or Bart PE, which means LUN0 needs to be CDFS. I assume this requires the USB controller firmware to have implemented this function. Just not sure if there are any off the shelf drives that support this.
^This. Unless you want an OS on the drive in the form of an image, I can't think of any reason why you would want a special partition specifically designed to store ISOs.