How can I set the preview thumbnail image default settings.

I would like to default all models to save the preview thumbnails as "shaded with edges" with a white background as default.  It currently saves the shading state at at save, and will default the background color to white or black depending on some threshold of the background color(light blue=white, dark blue=black).  I would like all parts and models to be saved in the same fashion no matter what the users settings are.