PrepareForTimeMachine is a program that allows the user to restore his current backup from a network drive (NAS).
Insert your MacOS installation disk and start your Mac. After loading, choose "Terminal" from Utilities and mount your external disk. Installer enable by default the DHCP for interface en0. If the NAS is configured for DHCP, than it will get a reachable IP address. To discover it, try to ping the whole submask using the ping tool.