Quick workaround:
I was working on a project whose budget literally did not allow for me to use AE.
So my solution was rather simple.
1. In the effects set keyframes for initial movement.
2. Add a directional blur to that layer/sequence.
For my sample I did it to a PSD of a title card. It animated downwards along the y axis.
I set the motion blur to increase as the layer/sequence went out of frame. Achieving the same look as a regular motion blur.
3. In My case: I set the initial keyframe for blur amount to zero then as it translated along the (y) I increased the blur level.
4. Last step, make sure the direction is in the opposite way of the motion.
Voila, there you go. Simple fix, at least it worked for me. I hope it works for you too.
Good Luck. If you have any other suggestions or questions feel free to ask.
Thanks,
Matt N.