This article was written in August of 2005, and I haven't tried the
techniques, but the second half of the piece ("Moving Music - A Step
Beyond") might be helpful...The tough part, as others have noted
here, is how to keep track of music that's been added to the central
library....
<http://playlistmag.com/features/2005/08/shiftitunes/index.php>
HTH,
Jack