Paul:
I took a look at this object and there are no rotation parameters. You have a few options:
1. If you know GDL, add a rotation parameter to the 3D Script of the object.
2. Without GDL, create a new object by viewing it in the 3D Window from the desired top and use the
Save 3D Model as command; in the Help files see Virtual Building > Parametric Objects > Graphic Creation of Custom Objects >
Saving 3D Models as Objects.
You should add a Signature to your Profile (click the Profile button near the top of this page) with your ArchiCAD version and operating system (see mine for an example) for more accurate help in this forum.
David