I've gave the script you linked to a good go but it doesn't feel like working.
I installed the Xvid codec it recommended even though I can play the files fine with VLC.
When it tried to muplex the audio and video it says something like "video" not found. Would use QuEnc to encode my file to mpeg2 be enough? I would like to use iDvd to do the actual dvd creation on my laptop.