fusion itself has a vector blur node, which you can use with the vectors that come from vray. probably you need to "massage" the vectors into the right format fusion expects. and be aware that if you render in 3dsmax y and z axis are not the same as in fusion
then there is a vector blur node in the free krokodove plugin set
and you can also get a version of Reelsmart Motionblur (which can also work without the vectors)
and if you got fusion studio you have the dimension plugins which can also generate motion vectors to use in the vector blur node