Just visualize the melody and lyrics, the song itself. As if your brain had its own media player. To do this, you'd have to know the song very well, lyrics and all. You kinda hear it very quietly after a while as you visualize listening to it.

For example, I just visualize all the songs from my favorite album by The Police, since I've been listening to that constantly for well over 15 years. When I visualize the songs, it's like I hear them going in my head. It keeps my attention from drifiting everywhere. I still haven't managed to do a WILD from it though, but I never managed to do a WILD from anything either.