Burning an AVI with subtitles question...

I have a folder containing a silent film in AVI with foreign title
cards, an .sub file and an .idx file. Supposedly the english subtitles
can be incorporated into the burned DVD. The instructions read: "This
xvid contains the original German intertitles. English
subs in vobsub format are provided. They must be placed in the
same location as the xvid to play properly."

Note: This xvid has dual audio tracks. Track 2 is a commentary
track.

I can't seem to figure this out with Nero, DVD Shrink or DVD Flick.
Can someone please enlighten me? Thanks...

Eddie