FC3: unable to boot from usb hard drive

[Guangwen He]

I installed FC3 to my usb hard drive and followed Simon's instructions
to add usb support in the new boot image at http://simonf.com/usb/
using "cpio" instead of "mount -o loop".  But when I booted FC3, it
failed. The error message is:

RAMDISK: Compressed image found at block 0
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

Anyone knows how to fix this issue?

Thanks,
Guangwen He