What do you mean "disconnected the hard drive?" You mean you physically unplugged the hard drive? You shouldn't have to do this.
Have you tried simply putting the CD in and rebooting while holding the C key? This should force the system to boot from CD.
For future reference, no software issue should EVER require you to open up a mac, unplug internal hardware, fiddle with jumpers, or any crap like that. Soldering iron troubleshooting is very much a PC thing.
I have been using Macs for 5 years, still have the only 3 I have ever owned. They all work, the oldest one (a G3 imac) has been wiped and reinstalled and booted from CD and all that dozens of times, including to fix a serious boot failure fault. I have NEVER EVER seen the inside of a mac other than when installing RAM.