Panther (10.3) was able to install perfectly on the older iMacs and Power Macs (Blue & Whites). Now, becasue a FireWire port is required, you cannot install on those machines. There are, however, two ways you can install it on unsupported machines. You can either clone a drive that already has Tiger running, or you can burn a compatible copy of the install disc. I will only cover how to reburn the DVD in this tutorial.
You Need:
Here are the general steps to follow -- note that iMac-specific 'no DVD' installation steps follow below this section.
function checkSupportedMachine(machineType){
var badMachines = ['iMac','PowerBook1,1','PowerBook2,1', 'AAPL,Gossamer',
'AAPL,PowerMac G3', 'AAPL,PowerBook1998', 'AAPL,PowerBook1999'];
Now, if you want to be able to install on all unsupported machines, just delete eveything in the square brackets. I changed my OSInstall.dist to (note: line break added for a narrower display; don't add one in the code!):
function checkSupportedMachine(machineType){
var badMachines = ['PowerBook1,1','PowerBook2,1', 'AAPL,Gossamer',
'AAPL,PowerBook1998', 'AAPL,PowerBook1999'];
With the code above, it enabled Tiger to be installed on an iMac and Power Mac G3 (Blue & White).Mac OS X Hints
http://hints.macworld.com/article.php?story=20051211074138859