I created a similar program for SC:BW called BWAI Launcher. It is a little different to what you will have to do because in the backend it used a separate program called an SEMPQ to open SC and inject a custom MPQ (containing the compiled AI's) into its memory, which would let the AI apply to any map you would play. Since there is probably no way to inject an MPQ into SC2's memory at the moment (and would probably be a tough thing to do), you will probably be limited to injecting the AI into 1 specific map then launching SC2 into that map. So your program would ask for a map to play, you would copy that map to a temp file, then inject your AI into it (remember, maps are just MPQ's) and run SC2 with the temp map.
Now I'm not sure which MPQ library you would use, when I was working on my SC:BW modding tools back on Leopard I compiled SFMpq for OSX myself, but then I couldn't get it to compile for Snow Leopard (and havn't even thought about Lion). I think I remember seeing some Cocoa (if you are doing Cocoa) frameworks but I never tried them out.
Anyway, good luck and if you have any questions i'll try to help!
Edit: Just noticed this thread was just necroed and esotericmoniker hasn't logged in in 2 years :(