Turns out that quicktimePro (which Liv has) can do the trick:
– Save desired text as a .PNG with dimensions of movie (say 1920×1080) and transparency.
– Open .PNG with quicktime player, select all, copy
– Choose a section of the target movie (in/out points) and
– Edit add to selection and scale
– Open Properties windows and play with the visual settings of the pasted .PNG video track
– Adjust Transparency (bottom left dropdown) to Straight Alpha
– repeat for as many tracks as needed.