Have you tried the Path Track in Sequencer? If you add your object to Sequencer, you should be able to add a Path Track and assign the spline as the guide for that path. You can then control the distance along the path with keyframes.
Have you tried the Path Track in Sequencer? If you add your object to Sequencer, you should be able to add a Path Track and assign the spline as the guide for that path. You can then control the distance along the path with keyframes.