Perhaps somebody with more experience can tell me why I cannot boot into OS 9.2.2.

This is what I did:

With my 733 MHz G4 I used Carbon Copy Cloner to clone a volume with a little used OS 10.4.11 and OS 9.2.2 onto an 8 GB USB flash memory stick. I can boot into the flash 10.4.11 but not the 9.2.2 except from the original 9.2.2.

Flash details:
Apple partition map
Mac OS Extended (Journaled)
OS 9 drivers installed

I would be grateful if somebody could tell me what to do so that I can boot into the flash 9.2.2 from both Startup Disk and Startup Manager.

I have put an update to my earlier message at:

http://forums.macosxhints.com/showthread.php?p=586158#post586158

Please use this new location for replies.

Here's what I did to be able to boot from an external USB drive on my PowerPC G5:

http://mediacaster.nl/usb_boot_imac_powerpc_g5.html

1. Be sure to partition the disk with an Apple Partition Map (i.e. not GUID or MBR)
2. Determine the partition where your bootable image it situated (e.g. an MacOSX DVD or DMG restored to a partion with Disk utility's restore). This might be disk1s3 in which case the partition number is 3
3. Restart your iMac while holding down Command-Option-O-F (Alt-Cmd-O-F). This will land you in Open Firmware.
4. Type:
dev / ls
to get the device tree/list.
Look for something in the output like:

/usb@b
/disk@1

As we're talking about a tree here, write down the complete path to this node. In my case it would be:

/ht/pci@2/usb@b/disk@1

5. Type:
devalias ud /ht/pci@2/usb@b/disk@1
In other words: make 'ud' equal to the path you found in step 4.
6. Now verify you got the right disk:
dir ud:3,\
(3 is the partition number you wrote down in step 2)
And look for a file with tbxi attribute, probably in:
\System\Library\CoreServices\BootX, e.g.:
dir ud:3,\System\Library\CoreServices
7. Then boot from it:
boot ud:3,\System\Library\CoreServices\BootX
8. Presto !
USB's your uncle.