There are AHT files for PowerPC, but no instructions to create bootable drive for them.

[strspn]

Hello,
There are several files for PowerPC-based computers (eg. PowerMac v2.5.2GMc1), but the procedure described in README.markdown for creating a bootable drive is for Intel-based Macs only. Specifically, the command
sudo bless --folder /Volumes/USBstick/ --file /Volumes/USBstick/System/Library/CoreServices/.diagnostics/diags.efi --label AHT

references an EFI file, a file that does not exist in the AHT file 018-2216-A.dmg (PowerMac v2.5.2GMc1). EFI is specific to the Intel-based Macs, while PowerPC-based Macs use Open Firmware.

I tried
sudo bless --folder /Volumes/USBstick/System\ Folder/ --file /Volumes/USBstick/System\ Folder/System --label AHT

but that did not work.
Thanks,

[estesmax]

Facing the same issue right now working on a Power Mac G5 7,2. I know PowerPC Macs require the boot drives to be formatted with the Apple Partition Map and (most?) won't boot from a USB device without a few tricks in open firmware.

@strspn Did you ever find a good solution?

I have a spare firewire drive to try with as well. Unfortunately I'm a little blocked from testing things out since this is my only PowerPC Mac and its not booting reliably enough to make much progress.