AutoCad 3D :: 3D Lines To Surfaces?

I regularely work with CMS (cavity Monitor Survey) data that is typically provided to me as a collection of triangular 3D faces that represent the interior surface of an open cavity within rock.

These files typically have 30,000 to 80,000 faces.

The last time I requested a survey the consultant indicated that their scanner was out of the country for repairs, but that they could generate a similar model by a different method.

What they did is shot many survey points then manually drew lines between them to give the outward appearance of the the normal deliverable. To the surveyors credit, he drew 3,800 lines to generate this wireframe.

My problem is that I normally have to slice the scans to provide planar outlines to our design engineers... and I can't slice lines.

Any way to generate these surfaces automatically? Is there a lisp out there for this? Essentially I would like to shrinkwrap it.

Working in AutoCAD 2000, but also have MicroStation V8 and MineCAD. MineCAD has a Tessellation function that is partially successful, but tends to join points together incorrectly and "fills" my cavity with random surfaces.