I don’t see how you can use TimeDelta in this way, and I don’t think it will help in this case. If the game is running at 60fps, and suddenly drops to 30fps, how will it know to skip every second entry? TimeDelta is no use here.
Agreed, that would be a good method. Here’s a link to a thread covering a Braid like effect. It should be reasonably easy to modify that for your purpose .