The different methods to control dynamically the speed of an animation usually work by skipping frames. That means loss of smoothness, precision and quality.
A better way is to modify the frame rate of the movieclip at runtime. By mike
This tutorial will teach you simply how to move a sprite with the keys on the keyboard, such as the arrow keys. Aimed at begginners who have minimal experience with Flash and no eperience with ActionScript. By Luke Knepper