Hey Greenpakto,
I believe the updating you are talking about is just Steam itself updating. If you found an earlier version to install or had backed the game files up before updating then you could install/restore that with your internet disconnected, go into the properties for the game through the Steam game tab and in one of the tabs there is an option to turn off automatic updates for just that game.
Whenever the game downloads and applies a new update it says it in the game tab next to that specific game, if steam requires a restart because of it then it will also pop up a restart request window when the update has finished.
But yeah, don't bother with all that mucking around...just wait for Rebellion to add support for ranked matches to the dedicated servers.
Cheers!
Valheru