well, 3 channels of video and 1 channel of sound in one Quicktime,
and with SetTrackEnabled you are done.
This however requires the end user to have Quicktime installed.
If that is no problem, it's very easy.
I would suggest you outsource it, will be cheaper than buying a copy of Director.
hth,
Bouke
http://www.videotoolshed.com/
smart tools for video pros