I am truely convinced there is a way to unlock Neo. Has anyone tried the Atari hint hotline? It is on the technical support website. Maybe then they will say the code!
Also, the Neo model file was hanging around on the PC game's directory, so there is a good chance it is also on the consoles'. I personally have GameCube. Maybe Action Replay can rename the files or something? I'm not exactly sure how Action Replay works though. It's worth a try!