You don't need another live CD if you have the install CDs. Just pop in the install CD, at the prompt enter "linux rescue" and follow your nose.
When you get a shell prompt, edit the file in /mnt/sysimage/... or "chroot /mnt/sysimage" and edit the file where you expect it.
At least FC5 had a rescue mode, I ain't up to FC6 yet.
If man was meant to fly, God would have given him a big brain and apposable thumbs.