Grampa,
This shouldn't be a problem if you build the model on a GE terrain from the beginning. Open GE and find the place where you want to build the model. Zoom in close enough so that you can clearly see the roof of the building you want. Keep GE open and open SU. In SU choose Tools-Google Earth-Get Current View. This will bring in the scene as shown on the GE screen. Now build you model on top of the roof image.
When you're finished with the model, you can view it in GE or upload to 3D Warehouse and the file will contain all the location info to place the model exactly.
Tom (fellow grandpa)