HELP! Trying to install OS 9 on iMac G3 Rev D

So, I have an iMac G3 Rev d (333 mhz) , and I got it installed with OS X 10.0.3. I would like to install OS 9 on it. But, I can't. Why? Well, because when I put in the disc and press the C key, the iMac COMPLETLY ignores the install disc. I've also tried running it in Classic (stupidly), and also tried using Startup Disc in System Prefs, but my bad luck still holds. I've tried it on my legit copy (9.2.1) and my un-legit copy (9.1). I've seen this fixed by removing the HDD when booting with other machines (PowerMac G3 B&W), but I can't exactly keep an iMac G3 open while installing an OS.