FLV container. How to add mp3 as audio track?

So I have an mp3 file. I have some frames inserted. Now I Need to insert this track as flv sound. How to du such thing (for frames insert I use this class http://www.zeropointnine.com/blog/simpleflvwrit开发者_开发知识库eras-as3-class-to-create-flvs/ )

This class explicitly doesn't support sound. I guess if you're creating the FLV dynamically it can't be too long so maybe it's worth just playing a sound on the side with the Sound object ?