So I want to control a movie clips rotation with the location of the mouse, with easing if possible. But I am having some trouble figuring out where to start. Can anyone help out on this?
You can use the Math.atan2() method to find the angle between two points. You can then use that value to start the easing of your rotation.
The best place to start is with a well-targeted search on Google, maybe using search terms like... "AS2 pivot mouse follow"
Here's one result from that search that might help you (depending on what you really want)...