Be sure you are in the "model" module (press 1)
Start with a polymesh cube:
Get -> Primitive -> Polygon Mesh- -> Cube
Set these values : U:3 V:3 Base:1
Get -> Property -> Geometry Approximation Changing the "Geometry Approximation" to the polymesh tab and setting OGL to 2 or [NUMPAD +] x2.
Switch from Wireframe to Shaded or Textured.
Turn on the "PolyMesh Hulls" in the view options.
Turn on the "Subdivisions" Pressing [ALT] and [NUMPAD +].
Select the polygon in the middle with the raycast [U] key.
Move this polygon using the Transform [V] on the z axis in front so it looks like the following:
Using the Select -> Select Adjacent -> Edges ([ALT] and [RMB] on the polygon), the 4 edges will be selected,
Mark Hard Edge/Vertex Edit
Now lets make the "hard" in terms of subdivision:
Modify -> Component -> Mark Hard Edge/Vertex
This can be done on the vertices also:
Undo [CTRL] and [Z] the previous steps back to the cube
Select Point Mode [T] and select (hold [SHIFT]) the 4 corner points
Set Edge/Vertex Crease ValueEdit
now go to the back of the deformed cube and select the 3 edges as sown in the figure:
Instead of Marking the component as Hard or not you can set a value for this.
Modify -> Component -> Set Edge/Vertex Crease Value