Installing Mac OS X 10.5 Leopard on slow computers

Mac OS X 10.5 Leopard requires a PowerPC G4 running at 867 MHz or faster. The G4 is required, but the speed really isn't.

Boot to Open Firmware using Command-Option-O-F. Then, assuming you are going to run the installer from the optical drive, do this:

dev /cpus/PowerPC,G4@0
d# 867000000 encode-int " clock-frequency" property
setenv boot-device cd:,\\:tbxi
mac-boot

This will fake the CPU frequency as seen by the installer until the next boot. This was tested on an 800 MHz eMac.