Update WW. You will now be able to successfully import de_cache. I was able to import it with the VMF and instances fmpone sent to me. I extracted the materials and models folder from the BSP into my game folders (so into csgo/materials and csgo/models ).
Note that if you already half imported it, you may want to go to your 3ds Max project folder/scenes/instances and delete any files in there before re-importing.
