Well its very easy:
Go to
http://seiv.pbw.cc/
There you have to register with PBW.
Then log in and search for "game listings" (here you see all your current game that your are in)and then "view all games" (all games currently playing on PBW.
Search for 1.67 star wars and click on it.
If you scroll down you'll see that there is a list with players and also an open spot.
Click on join, after this the host (me) can approve you and you will recieve a mail with the current turn. (this offcourse if you filled in the right email adress during the registration on PBW).
You can also download the current turn using the "download current turn" button.
Save it in your space empire\savegame directory and unpack it.
Then start SEIV gold (because the Version of this game is SEIV GOLD) and load your turn.
Play the turn and then if resolve that turn, it will make a ***.plr file.
You can download this file directly on the PBW site to the server, or you can reply your mail and attach this file to it.
Then the server will run the turn as soon as its gets all turns.
Then you will recieve a new email with your new turn etc. etc.
So for this game you only need SEIV gold.
So no MOD is needed.
Hope this will help you, otherwise there is also a nice manual on PBW.
Sparhawk