Once the .obj and VDM are created in Mudbox.
import the low level .obj into Softimage
Apply the VDM image to a "vector displacement Map" node in the render tree, then apply that to the displacement port of the material node.
Open an explorer window and under the object> "geometry approximation" , adjust "displacement" to get the proper displacement look.
In my case the 'displacement' inside the 'geometry approximation' node of the bull (inside SI) is set to :
Max Disp: 2
View Dependent >ON
Steps Min1, Max6