I'm pretty sure there's been discussion of this before. I think you'll find its not possible.
Maybe if you assign a shortcut key, you might be able to send a keypress through script? If you write your plugin to be actionable, you could use actions.
That's far too general a question to answer here -- as indicated, look at the AIActionManagerSuite documentation. Its been a while, but the dumbed down explanation is that you define an action & its parameters and then listen for action messages. When you see one that corresponds to one you've defined, you break down the parameters (and make sure they're what you expect) and then execute something.
