There is a SketchUp add-on for AC12 in Windows, but my preference is to use SketchUp Pro to export as 3DS and then use the 3DS-in add-on to convert them to library parts. Of course this requires having SketchUp Pro.
Thanks Matt, I had to reload my old Archicad 11 and the Google warehouse access under the file menu has disappeared. Any thoughts on how to get that back?