All this program does is sends "join" packets to localhost, and detects if the game is full or has already started. It doesn't send anything directly to battle.net, though I should probably try to figure out a way for it to detect if you're in a ladder game in order to make it "safer" for people to use. It doesn't write anything to WC3's memory space, and all it reads is your port address and host counter. Feel free to take a look at the source code.
In future versions, I should probably put some warnings about using it in melee games if I can't figure out how to include the functionality above.