Multiple Audio Tracks

We have an online course that's about 85% video, that needs to be translated into different languages. The customer wants the actual presenter in the video to be translated, not just the closed-captioning data.

I want to avoid having a set of FLV files for each language, because it will make the course enormous, probably over a gigabyte by the time we're done.

What I want to do is build a player that syncs FLV, MP3 and TimedText caption data. This way, we can add languages just by adding a new set of MP3 and TimedText files.

My concern of course is keeping the FLV and MP3 in sync. I looked into MPEG-4/AAC, but Flash only supports one audio track.

If I load and FLV and MP3 into 2 separate NetStream objects, or Media Components, is there any way I can guarantee they'll stay in sync? Or do I just do a time code check ever n number of seconds and have the video update accordingly?