The title says it all 
I am currently in the middle of trying to make TAS tools for Portal 2, and I was wondering if there is actually a definitive answer to this question.
I know about the TAS plugin for the OrangeBox engine. As far as I know this doesn’t support Source 2011.
Also, my goal is not just to create a plugin that lets you script TASs, its to make an actual program that lets you visualize the movements you are making, makes it easier to move your mouse, etc.
And his plugin is based entirely ingame. My plan involved heavy influence from an outside program