Thank you for posting this tutorial link, SB! I registered an account on Schtserv, setup my Hunter's License, and entered my Serial Number and Access Key information. I think my account to play online using the GameCube is ready to go.
I believe the only thing I need now is a long (25 ft.) ethernet cable to run from the living area where my router is to the room where I have my CRT and older consoles setup. However, I may try to test the connection in my living area with what I have on hand, to confirm I can login to the server. Will try to give that a go tomorrow night.