As I understand it, you want to show a 2D map (google, openstreetmap?) and add a 2D representation of the model to it? After that allow for selecting coordinates?
I am pretty sure it's already doing that on checkin, did you test it (I did and it is)? What is the adding wizard?
After checking generate geometry, add geometry to the map and have users add GIS coordinates to the project
adding wizard is also handy to show results of modelcheck after checkin?