Internet Sharing problem with Panther Server

Hello, I have a PowerMac G4 with an internal Airport card. Last week I installed Mac OS X Panther "Client" on that PowerMac and I managed to share my adsl internet connection (from Built-in Ethernet) to the Airport card simply starting the Internet Sharing service available in SystemPreferences->Sharing. Thus, my PowerBook could get the internet connection from the PowerMac via Airport. Now I installed Mac OS X Panther "Server" on my PowerMac, but I cannot find a simple way to share my internet connection as I did under Panther "Client" since the "Internet" tab in SystemPreferences->Sharing is no more available. Can anyone help ?