I'm attempting to install MintPPC on a 2006 12" PowerBook G4.

So far, I’m trying to follow the Net Installer Installation Instructions.

I’ve successfully created the USB Flash Drive of the installer, but
when I run “boot ud:,\\grub.elf” from Open Firmware, I receive the
Prohibitory Sign come up.

I can flash another drive with the Live USB if I need to attempt that instead.

How can I successfully boot off of my USB Flash Drive using Open Firmware? 

The DVD Drive inside the machine isn't functioning. I showed it to a local Mac repair shop, and there isn't an internal DVD drive I can get my hands on. My USB SuperDrive isn't functioning with it either since the Mac can't provide enough bus power to it.

If I can successfully boot/install MintPPC on this iMac, I’ll
probably send in a donation as a thank you for providing us MintPPC.

Thanks!