Tested it with Warcraft III and Hamachi between two Macs on the Internet and it works like a charm. My machine was set up to forward any UDP packets on port 6112 that was sent on my en1 interface and then forward the packets to the tap0 interface that Hamachi uses. The client on the other end would then be able to see my WCIII Local game.
Note: Since WCIII apparently doesn't broadcast on all interfaces, this app is required to get it to work using Hamachi.