I doubt it. But then, it isn't all that necessary.
Go to the point on the timeline where you want motion blur to stop. Split the layer(s). Turn off motion blur on the second section of the newly-split layers. Done.
Back in the days when 256 mHz was a wicked-fast machine and 512 MB was a boatload of memory, I used this trick all the time to speed up rendering -- you could cut a second or two render time off each frame, by golly!. It works like a charm.
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA