Using just Flash you can't. You need some audio editor to slow it down, for example Adobe Audition.
If it was me I would slow down the audio to 50% and change the frame rate of the animation to its half. When all the animations are done, put the original audio in and change back the frame rate.
Are you laying the audio in the timeline? Or are you playing the audio using Actionscript?
If you are using the timeline for the audio then you can set the keyframe for the audio file to "Stream" and then you can scrub the playback head along the timeline to find individual sounds or words, etc. You can then mark those points in another layer using key frame labels.
If you are using Actionscript then look through this article on how to work with cue points in the audio file.
Thanks! You are a lifesaver! I was able to change it and got the timing down perfectly! I cannot thank you enough!!
I just laid the audio in flash. I am a beginner and do not know how to use Actionscript yet. Thank you for the help!!