Are you asking how do you animate an Actor when a button is pushed down, and stop that animation when the button is released? Like for example, a walking animation when pressing the left key, or a firing animation when pressing the space bar? This scenario has what you're looking for . Just go through the code and check it out.
I was going to ask the same thing. You can always look at source of my gravityballs scenario. In the MyWorld and Ball classes, you'll find how to use the mouse press and put an image where clicked. Wouldn't take much to follow the mouse!