I have the same issue...
have you find any answers ?
You can not manage 3D models in a Central Library flow. Managing 3D models is only possible with the use of xDM.
You have to add the 3D information on a 'Design"basis. This information is locallay stored with the design in the design
However, starting with VX1.2 you can save the 3D mapping to the Central Library, making it available for re-use.
This is explained in the following document.