i know theres a way to use PhantasyStarOnline to connect your gamecube to your PC then using someother programs like GCNcrpt and GCNrd and some other stuff you can search the memmory of gamecube games and find memmory addresses that represent data in the game and then you can convert that memmory address and a value for it into Action Replay format and make your own action replay codes but i dont know exactly how to do it.. does anyone here?
Oh here is another site that you can check out also http://www.codemasters-project.net/portal-english/apportal/news.php .They both have some good information on hacking the GC.