Heh, I bet I know what you're up to... ;)
It's not exposed in the same way under 2.x anymore. There are still ways to root around in inventory from an action plugin under 2.x (eg, self._templar._available_variables), but the objects are effectively immutable, since 2.x action plugins run in a fork (ie, changes made would be discarded when the fork exits).
Drop me a note- I have some ideas about how to do what I suspect you're trying to do...
-Matt