Short article on how to manage rapid keyboard actions in Flash (Actionscript 3). The developer suggests developing an array to store keyboard events in case the action comes a bit too fast.
http://www.axelscript.com/2008/02/29/keyboardmanagement-for-games-in-act...
While I'm at it, I can post some other articles on programming keyboard events in Flash
Note: Adding keyboard events can enhance accessibility for motion impaired users since they don't need to manage the mouse so precisely.