Hi There,
You may be able to do what you want using only SU by exporting an AutoCAD .dwg file - but only if you have the 'Pro' version, SU 'Free' does not have this feature.
To make the export work correctly...
Your model units must be inches or millimetres (maybe metres is possible in newer Corel versions?)
In SU, turn off perspective with the menu item 'Camera -> Parallel Projection'
Using the 'little house' menu bar, select one of the standard orthographic views (top, front, left, etc...)
Now export the file (Export -> 2D Graphic), selecting the AutoCAD .dwg format.
Now import this file into Corel - after selecting the file a pop-up window will appear. Choose the units to match your SU model, and make sure that the "Reduce Nodes" option is NOT ticked. Place the drawing by just hitting 'Enter' - if you try to place it with the mouse, the scale will be changed.
Use Corel's 'Weld' and 'Close Curves' tools to tidy up the imported drawing (shapes will be made of many individual lines that are not joined together).
Take care when cleaning up the drawing in Corel - for 3D objects you will often get many superimposed lines in the imported file. I find that it is sometimes simpler to use the import only as a guide for 'tracing' new Corel geometry (for making true vector curves etc.).
If you are using the free Sketchup version, you may be able to use the 'SVG export' plugin from FlightOfIdeas - but this only exports individual faces, so there will be much more work to re-construct the drawing.