A few friends of mine on Steam are trying to get this game to run multiplayer, but for some reason every trick we try (aside from him using a DMZ to host just himself and I via direct IP) fails.

Our latest attempt was to use Hamachi, but a few of us keep getting some kind of "Inbound Rules blocked" error that none of us can seem to fix no matter what is tried.

Dose anyone here have a surefire way of playing 6-Player Multiplayer for Starfleet Command 1?

Only just got the game, but I have used "Tunngle" to connect and play with others with other games.
It's like lan playing, but using the internet.

You start Tunngle and the others join you, you start a lan game and they can join you through lan on the game.

If this game has lan, then it should work for it too.

Evolve is another alternative worth checking out.