Iray for Maya 2.0 takes the values set in the Rendering Settings and applies is it to the object.
Rotation Value
Set Rotation Value as a per object override for the selected object. A detailed description of the attribute Rotation Value can be found in chapter 6.2.5 Motion Blur attributes
Spherical
Set Spherical as a per object override for the selected object. A detailed description of the attribute Spherical can be found in chapter 6.2.5 Motion Blur attributes