Assuming you are using 3D Invigorator Pro, you can set up the door pivot by creating the same door twice, and lay them side by side. Make sure the doors are in the same set, and when the program calculates the center point of the set, the pivot point will be at the center of the 2 doors and basically be at the "hinge" location. If you need to, choose the "Recenter Pivot" command in the "Set" pulldown menu located in the AE Effect Controls panel. Then, you can go back into the 3D Invigorator interface and make one of the doors invisible, or delete it from the set.
When you rotate the door, the pivot point should be at the door hinge.