root.plist dymamic change of display information

Question

How can one possibly display an information paragraph within settings.app? I'd use root.plist and NSUserDefaults group footer. But how can I link these two together, so the information can be modified dynamically from the app?

I would like to display information like: @"Your secret user code is: %d", userCode. And change the userCode every time the user e.g. purchases something.