They are available in all modules - but you'll need an instance of the AHPreferenceManager to get the values.
The tutorial shows how to have an instance of the AHPreferenceManager as a Process_Global in one module.
Now you can access that instance from the module it was declared in and also from any other module.
To access that instance from a module which it was not declared in you prefix the instance name with the name of the module it was delcared in:
Main.MyPreferenceManager.GetString("port")
Here i'm assuming that in module Main you have declared MyPreferenceManager as a Process_Global.
From module main you'd use:
MyPreferenceManager.GetString("port")
From all other modules you'd use:
Main.MyPreferenceManager.GetString("port")
Martin.