You might have to wait a while. I don't think there is yet any work on the latest incarnation of this idea. I have no idea how the ealier ones worked (or even if they could possibly have worked) and I'm pretty sure the new idea hasn't had any implementation yet.
If your problem is being behind NAT (as is on most home routers) and you can't forward the ports, this project should fix it. If your problem is something else, or if you can forward ports, there are probably other ways around the problem.
To join games, you need to be able to accept connections on port 47800 UDP (well, really the first port the game can bind to in the range 47800-47807).
To host games, you need to be able to accept connections on ports 47776 UDP and 47777 UDP (well, really 47776 and the first port the game can bind to in the range 47777-47784?). But if (and only if) you are behind NAT, you also need to run NATfix to be able to host. Careful about this one though as there is currently a buggy version floating about (the newer one).
In short, being able to forward ports 47776-47807 UDP should allow you to play. (Provided you run the NATfix if you're behind NAT and you are hosting).