> "stories/stories_by_category.php?category=5"

> but the stories all come up under
> "stories/showstory.php?id=12345" 

> so how do i block the other pages on the story page
> except for the links with the &page=2 in the link,

get catalog 5 + story first pages + continuation pages.
Try:
max depth=2 
+*page=*