How can I inherit from script class?

So, I'm writing a class within my script. How can I inherit from the script's instance, so the class automatically gets access to local GridTerminalSystem, Me and other neaties? I can inherit from Program, but that is a type, not an instance (and does not contain local term in GTS, local PB in Me, etc). I can also pass GTS and Me into class constructor and then save them within class variables, but I'm looking for direct inheritance, not for workarounds.