Sounds like an interesting task. If it were mine, I think I would use markers to define a duration first (i.e. listen to the tune, and enclosed a desired phrase on the timeline with markers - "my Bonnie lies over the ocean" for example). Insert a video track to the timeline.

Then, with video preview enabled, right click the blank video track at a point that is smack dab in the middle of your markers, select the appropriate text generator plugin (I forget exactly what it's called), type in "my Bonn . . .", and close the plugin, position the newly created text event in the middle of your markers if it's not there already. Right click on that text event and select edit generated media, then, use the nifty position tool to fine tune the position of the text as you want it to appear on the screen (you can watch the position change on the video preview if you're timeline cursor is positioned over your text event), making certain your placement and text size allow your phrase to fit safely within the boundaries of the viewing screen.

Then, just to be safe, close the text generator, and play that section of the timeline to make certain the position is where you want it so that the text appears/disappears at points appropriate to someone dependent on the text to sing along (you'll want the text to come up a bit ahead of the tune, I'd guess).

To add a professional touch, you'll probably want to add fades at the beginning and end of each text event.

Unless you are subtitling Wagner's Ring, or creating a bouncing ball, I bet you'll be an expert at this by the third phrase.

Sounds like a lot of fun to me.

Good luck.

Caruso