Unfortunately for the standard music player (music), you cannot modify the @@info_rolling_message to show just the song playing. I’ve tried substituting other @@ variables to achieve this but have never been successful.
However, you may be able to manipulate the other music players (spotify, Pandora) to show just the song title. You would probably need to play around with the variables provided in the xml files of these music players to see if you can add just the song title to the home screen. I would also suggest you look in the theme section of the live hub forum as someone might have already looked into this and have something usable working.
