Icecast is fairly gay, and doesn't list on shoutcast.com where there is a larger listener base.
as for the main thread.
Ok on demand only streams a single file, that's what it's there for.
You could use the intro play facility, append all the files into one mp3 and set that as the intro, then set a maximum listen time equal to the lenght of the super mp3, listeners can tune into your station, listen once, then they get dropped.
That will possibly acheive the desired effect.
"My bounds know no shame