Manipulating pre-concieved keyframes with AS3

Hello-
I was wondering if anybody has tried to do this-
Lets say I have an animation of 5 keyframes that has already been executed the old fashioned way, by hand.
So, can write some actionscript that will allow me to scrub through those frames of animation dynamically in response to input from a user, or specifically in what I’m trying to do, the amplitude of a sound file I’ve loaded externally?
I have tried to use the leftpeak property in response to the sound playing but I have had trouble with the playhead just playing through the keyframes unnaffected, or running into errors I don’t understand.