You sure it wasn't O&Gs, in which case it would've been The Ziggurat of Doom? I think that was the first ever WFB scenario, but they might have redone it for another edition too. There's lots of results on google for it.
That looks familiar, but I definitely remember it being Skaven in it. Same concept though. You're probably right. They just updated it. I think that they even played it out in one of their in-magazine batreps.
@ Bureaucrat of Chaos: I don't have access to that issue, but that sounds like it would've been around the correct timeframe.
My armies: Empire, Dwarfs, High Elves, Wood Elves, Dark Elves, Lizardmen, Skaven, Tomb Kings, Ogre Kingdoms, Orcs and Goblins, and Skitarii (40K).