Need help with iMac

[malync2]

I have two 350Mhz imacs (256M RAM) that someone installed OSX on. I want to go to OSX.3 on these, but it won't let me without firmware updates. When I try the firmware updates I get a message saying that I need OS 9.x in order to continue. I set them to boot from OS 9 on reboot, but they won't reboot. I can't get the machines to boot from the OS9 CD, and now they won't boot back to OSX either. I get a happy Mac screen like OS9 is starting, but they just freeze there. Is there a way to install anything on these without removing the HDD and formating it in another machine? I've tried resetting PRAM, but no help. Thanks, Mark.