You can import X, Y, Z coordinates using the .pts format - columns of ASCII coordinates with empty newlines separating groups. Once in Caedium the points will be represented as groups of vertices which you can then select and fit splines through to define edges. However, then creating faces from those edges and making sure the faces define a watertight volume can be difficult.

A better option is to use a CAD system and model the surfaces directly as a solid.