I've been trying to figure out how to get link play working.
So far I've discovered the command line flag "-netcoophost=1" on "-playerside=1" causes the process to bind to "TCP:0.0.0.0:3742", and I've also seen "-playerside=2" try to connect to "TCP:0.0.0.1:3742"
0.0.0.1 doesn't seem right, I hot patched it to connect to 127.0.0.1 and I swear I got it to somewhat work once, but haven't been able to reproduce. I've been logging "accept" calls on player1 side but I haven't gotten any hits.