Stonehell on the Borderlands
1. Take one Dungeon Module B2: The Keep on the Borderlands. Remove the ravine containing the Caves of Chaos, using a sharp knife. (A metaphorical one is ideal.)
2. Take one Stonehell Dungeon. Stuff the box canyon containing the dungeon into the space vacated on the Borderlands map by the Caves of Chaos. It should fit snugly.
3. Bake in an oven (again, metaphorical is best) set to your favourite edition or retro-clone.
4. Serve with a garnish of rumours, random headgear, etc.