This works if you want to highlight certain chords (without lyrics) in a single line:
[00:10.00]C [00:20.00]D [00:22.00]F [00:24.00]
The current layout system is not able to handle the case where the same timecode is used in more than 1 line. I don't think I can add this feature without a whole new way to do highlighting. Maybe in version 4.