Right now you can't ...

Well.. actually you can! (sort of)

If you create a soup playlist with the layers:

Genre -> Artist -> Source

then expand the playlist so that you can see the albums (source) and then select one of them, so that you can see the track listing, then add the Track column and click on it's header to sort by Track Number.

If you then go though and right click on the idividual playlists and click "Set Playlist Order". The tracks will then play in the correct order on the player...

I know that you have to do this manually for each album, but at least it works!! - and dosnt really take that long to do (depends on how many albums you have i guess)

Rich