Closed captions?

Hi, I’m curious does anyone know of a way or a tutorial that might help me add captions to a flash video with actions?

I know how to add captions to flash that I can convert into a flv. but interactive flash cannot be converted.
I believe there is a way to do captions by adding the words on their own keyframes but some of the video’s I need to caption have no real keyframes just scripts pointing to a audio holder such as:

  
     stop();
bgSound = new Sound(this);
bgSound.attachSound("mentorintro");
bgSound.start(0, 1);
bgSound.onSoundComplete = function() {
    _root.gotoAndPlay(3);

}; 

this takes a button on the stage and begins playing the audio file, once that has stopped you can choose another button to play another audio file ect.

is it even possible to caption?

Thank you,
Jeff