I got gameranger working, however I have not been able to actually test if it can launch games properly. I only have two games that require gameranger for multiplayer, and that is Stronghold 2 and Stronghold Legends. I do have a plan to test those games if I can get a friend to purchase those games on Steam.
One important thing to note is that according to WIneHQ, it appears that it works for some games, but fails for other games.
The page booman references details all the additional libraries you must install with PlayOnLinux for the gameranger to be able to launch properly.