I'm familiar with scrambled. Simply "unwrapping" an imported objects UV's, especially from a CAD program, is usually not a good idea in Carrara. Carrara handles it's own UVs on objects beautifully, but not with certain imports - simply because of the way other 3D apps generate the polys and UVs. Here is another option. Once in the vertex modeler in the Globals tab of the Property Tray, you can delete shader domains and then create new texture domains by selecting all of the polygons for a given area and then generating a new shading domain. Doing that does give you some improved control over the UVs in the Shader Editor. Creating new shading domains won't unwrap the object differently for the UV editor, but it will allow better results with the Flat, Cylindar and Spherical mapping options in the Shader Room. Also, I personally don't have Rhino and am unfamiliar with it's texture tools. Does it have a tool set that would let you import the .step into it and then create an new UV map. Then you could simply export to Carrara from Rhino. Kind of the long way to do things...