The key to inserting a dwg file onto a vertical plane is to rotate to vertical in CAD first then link in as normal. I needed to put in a basement piled retention wall elevation into the file to align the designed capping beam. What I did was link inserted the elevation onto the plan view in revit to line up the grids. I then rotated the elevation in autocad using x axis and reloaded the link and voila. It helped that I was in the 3D view to see the change.