Find And Bind maxscript will scan your hdri and find the sun location.
After that,it will create V-Ray sun in this position and bind it to V-Ray Dome light.
You can rotate the rig by rotation the dome light or in the VrayHDRI map(horz rotation).
http://www.scriptspot.com/3ds-max/scripts/find-and-bind-vray-hdri-sun