Yes, my art path was: putting various meshes together (maplet, FLE etc.) and position lights in slimshady, then import and lightmap it in Gile[s]. Too bad I ain't got Gile[s] on my current machine.
The engine then taints the grass based on the underlaying ground color/darkness, and also dynamically darkens the NPCs (pre-determined based on their paths) and the player hand/gun (dynamically determined based on position).