If you absolutely must be able to brawl Brawl and Melee with a stick, then your only options are to use a UPCB, or wait a couple of months until I get GameCube added to the Cthulhu.
You could use a hacked Wiimote like suggested above, but that would only help for Brawl. You could try to get an analog stick and wire that to the left analog stick on a GCN controller, but you’d still be left with a bunch of stuff you couldn’t perform (like Peach floating dair), and you’d be talking on hell of a lot of work getting the wiring all together, and that same stick would be useless for putting the other two pcb’s into.
I’m not trying to make it seems like I’m a salesman pushing for a sell; I’m a geek who likes his sticks. I’ll spell out all of the different options you have, but if Brawl is a must have in your stick, a UPCB or (eventually) a multiconsole Cthulhu is the best way to go.