The common pipeline for Google 3D Warehouse, 3DXchange and Google SketchUp is as below:
Click the Google 3D Warehouse button on the tool bar.
Search for the desired Model. Click Get Model button. You are prompted to save the model into your desired directory.
The Model Loaded into 3DXchange
Click File/Edit Original SKP File (Ctrl + K) to invoke SketchUp if you want to re-edit the model.
Click Save in SketchUp after you finish editing.
Model Edited in SketchUp
Click Reload (F5) button to reload the edited model into 3DXchange.
Result in 3DXchange
For more details, please visit https://www.reallusion.com/iclone/3dx_pipeline.asp