Hey spike.
once your 2142 is patched to 1.5, all you need to do is run the 1.4 install. You then launch the game via the launcher it places on your desktop- which downloads and installs updates automatically.
Once it is finished, you are ready to go.
jump in, log in and then set up your server list options like so:

make sure your view distance is set to 100% and join a server! If none are populated (as sometimes happens) join a small server and mess around/practise with guns vehicles etc while you wait for players to join.
''Its over. Angel won.'' RSF Gurd