Which program are you using to burn the discs or create the USB installer and which speed have you selected for burning the discs?
You mentioned in the other post that the computer boots up ok with OS X 10.2. If you can't get OS 9 to install via CD/USB then it seems to me that the easiest solution is to use OS X to install OS 9 - which is exactly what I did with my iMac G3 whose CD drive is faulty and I'd been unable to create a USB installer for OS 9.
Create a OS X partition with a size according to the frequency that you'll be using it.
Create a partition for OS 9.
Copy the os9general.dmg (which will give you 9.2.2) onto a USB flash drive - or a FireWire HDD if you have one.
Copy the os9general.dmg file onto the desktop in OS X.
Open Disk Utility and drag os9general.dmg into the left hand side of Disk Utility.
Select restore from the menu and drag the os9general.dmg file from the left hand side of Disk Utility into the Source field and drag the OS9 partition into the Destination field.
Disk Utility should look exactly the same as this image:
Click onto the Restore button and click continue when asked, as shown below.
After the copying process has finished, go to System Preferences and from there to Startup Disk.
9.2.2 should be present as a boot option from the OS9 partition.
If you want the iMac to boot into 9.2.2 by default, make your choice and click restart. If everything has gone correctly, OS 9 will boot up when the computer restarts.