Ambient occlusion and curvature are calculated after displacement in Corona, therefore those maps cannot be used as displacement drivers. If you want to replicate this effect, you can do this like in the tutorial - select needed edges, create spline shape from them and use that shape to drive displacement, or boolean. My attachment shows how to do the former, but if you want to go the boolean way, then apply renderable spline modifier to the shape, give it some unevenness with noise modifier and apply Corona slicer material. On the other hand, if you want to go fully procedural, you can use 3ds Max data channel modifier. I think there are few examples how to use data channel in the forum and you can google many more on the internet.