Change ports used on dedicated server?

I have a company setting up a network of dedicated servers ready for my launch.

They need to be able to update the port so they can run several instances on a single box. I can to add an exec function to update the ports at runtime via command line.

Is this just a case of updating the conf var in the ini files?

Not tried it as yet but I assume you can adjust the port via the command line at start for each server instance, see section Network and Port