You're welcome! I made it for myself, but since it has the potential to help others, I wanted to share.
Here is a fairly comprehensive list of the desktop Macs it will boot:http://www.everymac.com/systems/apple/powermac/
Anything with any type of PowerPC 603 or 604 CPU. Generally speaking, all of those have PCI expansion slots, so the kernel and ramdisk supplied with MintPPC will boot with little or no modification, only sometimes requiring extra kernel boot parameters. The ones marked 'Processor PowerPC 601' unfortunately have Nubus instead of PCI, thus they almost always require a custom kernel (Not that it is impossible, it just requires having a running PowerPC Linux system to compile a custom kernel! Ditto really old 68K based Macs either with a cross-compile (crosstool) toolchain or already running on a 68K Mac!). And of course all the Beige G3s which also can't boot like New World Macs, in spite of having a G3 CPU.
And here are the laptops (Powerbooks) that will work:http://www.everymac.com/systems/apple/p ... rbook.html
Anything from the Powerbook 2400 on down. The 1400 was apparently considered "Nubus" based (see above).
My Powerbook G3 has SCSI and serial, the next series had USB and SCSI, and the final major revision had USB and Firewire. Every Powerbook G3 before the final Pismo model, which had Firewire and USB (New World, or so I've heard), is Old World and therefore would work with my CD. http://www.everymac.com/systems/apple/p ... ok-g3.html
As an aside, the first Powerbook G3 (aka Kanga or Powerbook 3500) actually is unsupported by OS X! Thanks Apple! And thank you Linux!
When I get bored, I may compile custom PowerPC kernels for Nubus PowerMacs, or even custom kernels for 68K Macs. The Nubus PowerMacs have 60-110mhz CPUs (ouch!) and I no longer own one, or a 68K Mac, though my main workstation was a Quadra 650 until 2002 (heavily upgraded of course!).
P.S. I think this makes MintPPC the first Linux distribution that can say 'we have a CD that boots Old World Macs!' The CD can boot any Linux PowerPC distribution with the right kernel and ramdisk, but I haven't modified it for other distributions, yet except for Karmic Koala (obsolete even by Linux standards!).