Help installing OS9 on iMac G4, no optical drive, using Firewire HDD

[bantamug]

Hi,

I've got an IMac G4, 6,1 1Ghz 15" / 2Gb RAM running Tiger off a 240Gb SSD which I imaged from the original hard drive.

I'd like to install OS9 Lives as the sole operating system on this device - mostly as a retro gaming and distraction-free writing machine.

It doesn't have a working optical drive, so I'd like to do the install via an external Firewire drive. I've used SuperDuper to clone the original IDE Tiger install to the Firewire HDD, booted off it, and imaged the OSX install back to the new SSD so I know I can boot from this drive.

I've done the openfirmware modification described here: http://mac-classic.com/articles/mac-os-9-on-unsupported-systems/

What I've then done is create a 100Gb partition on the Firewire HDD with OS9 drivers installed, and "restored" the OS9 lives for previously unsupported G4s ISO from here:  http://macos9lives.com/smforum/index.php/topic,2143.0.html
 
I hold down the option key on boot and the firewire HDD's OS9 partition appears as an option, but when I boot it, I get the grey disk with a question mark on it. 

Any suggestions on what could be going on here?

I've also tried to mount the above image and run the  "Application Software Restore" from OSX in classic mode to see if that can restore to the internal drive, but it exits with an error saying it can't close Finder.

Are there any other suggestions for booting and installing that OS9.2.2 image onto my IMac G4 without an optical drive?

I've got USB sticks and a USB CD burner, an M1 Mac Mini and an i7 MacBook to work with! Thanks!