When we worked up our procedure for importing Lidar into Civil3D a couple months ago, we realized there were way too many steps and way too many hoops to jump through. Hoops preparing the data, through Recap to prepare a RCP/RCS, through Civil3D creating a point cloud, and finally creating the surface. Highly trained professionals have more important things to do with their time than spend it like a well trained circus animal jumping through hoops, so we did something about it.
Like many things in Civil3D, they can be done but how it’s done isn’t so obvious. In the process of adding a DEM surface to your drawing you may notice that you can’t project it to another coordinate system (that of the drawing). Here is a step-by-step procedure including assigning a coordinate system to the current drawing.