So yeah, I've been trying to do it for 3 days and I don't want this time to get wasted. Here is a guide that will let you set up a private server for your friends within 1-2 hours.
INSTRUCTIONS FOR HOST:
INSTRUCTIONS FOR CLIENTS:
I hope, that I'll help at least one group of friends to play this game.
To admins: I will not answer to this thread. I registered just to write this one post and disappear forever. So feel free to edit it. I waive the rights to what I've written above.