I don't believe there was a pamphlet about that diorama in the original monogram Devestator kit, however it's correct that the diorama is briefly discussed in Shephard Paine's How to Build Dioramas (which is from Kalambach publishing, by the way). He shows how he immersed the model in a medium he used to depict water, which was contained in a baking pan, and then pressed wrinkled aluminum foil on the still wet gook to make a wavy surface. Brilliant stuff.
I met Shephard Paine once at an IPMS contest. I almost dropped to the ground and did the "we're not worthy" routine from Wayne's World.