Are you running from cd or a hd install?

/etc/hostname is the name of the machine

The file you want to change is /etc/hosts

If you are running from cd you will have to save your new /etc/hosts file to a floppy, zip, thumb, hd or persistent home. Then you can remove the existing /etc/hosts file and use your new file.

More info about your system and network would help.

~rock