[CONNECT C++] Assigning a GCS to a raster attachement

I've got code that attaches a raster file. However, that raster has no GCS, and I wish to assign one. I can use DgnRasterPtr::SetDgnGCS( DgnGCSCP ) to "assign" the projection, and I *think* I need to create a GCS using RasterDgnGCS() class, but I can't figure out how to do it.

Bruce