You will have a csv file where you can assign any runway and any terminal to a position with a frequency (in multiplayer mode you will have to use frequencies), and up to 6 players can control an airport.
Do you want to split north and south? No problem.
Do you want to split ground and tower? Sure thing!
Or do you want to combine positions and have a north tower, north ground, a south tower and a south ground? No problem either.
Oh and you've got another runway that handles cargo traffic only? Assign it to the 5th position! Too busy? Let's split it up even further to ground and tower too and let 6 controllers handle a major airport.