This sounds like a plausible solution and better than what I had proposed in the 3D SceneEdit thread, but it could also tie into it, too.
We create out master mesh, invisible mesh, and proxy blocks(waypoints, lights, cameras) in a 3rd party editor. When loaded into SceneEdit, it will substitute cams and lights in place of these proxy elements and use whatever values are included in the external file that Mnemonic mentioned. We then export the master mesh, lights, and cameras out to a format that can be used by a specialed rendering app like POV and make our renders there. We also save out the special 3DS file containing the invisible mesh(by using a yet to be created "export selected" option or only saving out elements with the special prefix names like "blk", "walk", etc), waypoints, lights, and cameras and the engine uses this.