I had seen the previous post on setting up a software base station via the terminal, but I couldn't get it to work for the life of me. I then saw this free ethernet router program called geeroute.
You simply install the program, and set the client machine with the correct name server on your network and set the router address as 192.168.150.1. It worked with an ethernet network, so I wondered if it would work with airport.
So I just set up the Airport settings on my G4 with 10.0.1.1 as the Airport IP (like they used on the Software Base Station) and set the subnet mask as 255.255.255.0. Then I used 10.0.1.1 as the router address on my Pismo. I gave the Pismo the IP address 10.0.1.6, set the subnet mask, and put in the name server.....and it WORKS!! You can have a software base station up and running in less than 5 minutes!

