Can you explain what specifically are on the slides? Is it a picture with a caption or a genuine comic slide? If it is a captioned picture, then it would be PROSE, as it's technically a short story; if a comic, then it would be COMIC. I would look to PROSE: Doctor Who and the Daleks as a sort of example for this kind of thing.
Also, are these stories officially licensed? And if so, are they original stories or clippings from TV broadcasts? I feel as if more information is needed if we are going to mark it as a valid source.