Initialising network with CD in iMac


I had an answer to this one before but this is slightly different. I clicked the wrong option on my PPP settings and now when I try to boot OSX, I get as far as "Initialising Network" before the start-up hangs. It's been like this 30 minutes now. I wanted to boot from a CD (OS9) but, stupidly, I have a music CD in there at the moment. Holding the mouse button doesn't have any effect. Any ideas? I will need to reinstall OSX I am sure but how do I get the CD out first?

Thanks a million

iMac DVSE (Graphite) 128MB, 12GB