[G4] How to run Disk Utility Aid on Mirrored Door G4

[Tracker at aol.com]

In a message dated 5/8/03 9:18:53, kriss at qsl.net writes:

<< Since the most current mirrored door G4's will not boot from an OS 10.2 CD,
how do you run the Disk Utility to repair permissions, etc?
 >>

What have I missed here? If a MDD G4 won't boot from an OS-X v10.2 CD, then 
how in the world can owners do an OS installation or upgrade?

There has to be some way to boot to an external device, doesn't there? Kindly 
explain to me how this is done without being able to boot to an OS-X v10.2 CD.