I think there are a few ways of solving your problem:
1. You could try to run linux in non-network-mode
at the bootloader hit ctrl-x for text mode and then type
"linux s" or "linux 2" (i don't know if this works with grub...)
If you're lucky you won't get any network support and in this case maybe your softmodem will not start.
If this works, you will have immediate root-access to your pc
if this doesn't work,
2. try booting from your first redhat installation cd
on boot loader choose the rescue-function. your installed system will be mounted under "/mnt/sysimage" i believe.
So your etc-directory should be /mnt/sysimage/etc
if this doesn't work
3. get a knoppix-cd and boot from it.
knoppix is a linux-distribution which starts from one cd without touching your system. But it enables you to mount nearly any partition of your pc i think. So you can search for your etc directory and edit your config-files.
get knoppix from
http://www.knoppix.org
if this doesn't work
it would have been faster to reinstall your system
