Ok, so I'm going to say that Gamecube is possible but after looking into PS2, I don't know there. First of all, it's ugly. Second of all, the analog control for the PS2 triggers isn't going to match nicely with the CC and GC anyway, in a physical sense. The CC and GC both have quite long "trigger pulls" for their analog, whereas the pull on the PS2 triggers are almost nonexistant (which is why they call it pressure sensitive). So I will definitely put the effort in to try to add GC analog triggers, but I probably won't even bother with them on PS2.
Hell yeah! We're gonna have our Project: Melee on WiiU really soon!