Well, as far as I understood your mail, you tried it once with no succes, than you removed the PCI card ... did you also try just to use the other one without to remove it?
Furthermore, what happens if you do a 'modprobe pcnet32' ? Any error messages?
I've tried 5 or 6 times, sometimes with both cards installed, sometimes just with the embedded one , the only operation I can do is to select "load Network card module" from the installation menu. I'd like to do a test like modprobe , but I don't know how to get a shell prompt during the installation procedure, you know, I'm booting via the serial console and I see the output on my machine by calling ssh to connect on a machine directly connected to the rs6k. eg: serial ssh RS6K -------- MACHINE1 -------- MYMACHINE M.