Well, I had assumed that it would work like with regular, non-3D placemarks, i.e. that an abbreviated marker would appear in the "Keyhole BBS" layer, which would contain only the name, description, and a "more" link to the forum article with the full KMZ/KML file.

However, since there is no layer for 3D-models in the Keyhole group, I'm starting to wonder...