I was successful by opening the Revit .rfa file/part that I wanted in the Revit Demo and saving it as a .dwg, then opening the .dwg as a new library part.
Now I have it as a new .gsm.
It was a surgical lighting boom. Now I can turn all the Revit parts I want into .gsm parts until my demo runs out. ThenI will have to find someone who has Revit to send the parts to and have them saved for me as .dwg
It's manufactures parts that I am usualy after rahter than building files.
I haven't tried it yet by saving the Revit file as IFC and then open the IFC with ArchiCAD.
The reason I think I prefer to open as new .gsm is because I can do that with out closing the drawing I am working on or having to open another instance of ArchiCAD.