How to make dropthrough and climbable layers in Paper2d tilemaps?

Hi all, I just watched the recent paper 2d tutorial here → Getting Started with Paper 2D | Community Led Training | Unreal Engine Livestream - YouTube. At 28:20 he shows dropthrough and climbable layers in the tilemap as layers. I have seen where others drop single sprites and blueprint them on the forums, but how do you do this within a tilemap layer?