If you go to the NWDA site, there is already a set of objects to use as leaf litter - but perhaps you are thinking of another kind? In that case, sure, if it can be modelled, then it can be transferred into TG2. If you could find what you are looking for on one of the sites that sells 3D models, as long as it is in .obj format, or could be converted unproblematically to .obj, then TG2 should handle it.