You can map UV texture coordinates by specifying user-defined planes for UV projection using the Load Projection option within the Automatic Mapping feature.
The Load Projection option uses a polygon object that you specify from the current Maya scene. The object can form a cage around the object or be comprised of separate faces that intersect each other at its center. The Automatic Mapping projection manipulator updates when a user-defined object is specified for projection.
Criteria for user-defined projection objects
In addition, it is useful to know that:
To load a user-defined polygon object for use with Automatic Mapping
The existing UVs for the object appear in the UV Texture Editor’s 2D view.
The automatic mapping projection manipulator appears centered about the object in the scene view with blue projection planes that correspond in orientation to the planes of the Load Projection object you specified. That is, if the Load Projection object has 8 planes in various angles of orientation, the projection manipulator displays similarly.
You can unitize the UVs for the Load Projection object prior to projection so its UVs reside in the 0 to 1 texture space. While this will make the projection manipulator appear more centered about the polygon object it may not provide the UV mapping results you were expecting as the UVs will be projected similar to having explicitly specified the Overlap feature.