Alternative element image using automation?

[dmf]

Can anyone advise how via automation I can assign an alternate image to a diagram object?  I have a set of composite elements on a diagram whose appearance I want to be a scalable representation of the diagrams they contain.  I can do this manually by saving each diagram image to the clipboard, then manually setting the appearance of the parent element.  I know an alternative is to stereotype the composite elements and set the appearance that way, but that still involves considerable manual work.