I believe this will best be done in the FORMS environment. I would first create a plane close to the average surface of the lense, then in forms, create a T-spline plane, or flat, on that plane. This T-spline plane can then be manipulated to match the curvature of the scan of the headlight. That T-spline can then be used to split the cylindrical body you have to give it the profile of the lense.
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