I've had some luck setting up collision objects to get the cloth to fold and twist as it falls. A couple of primitives straight from the library will do. One issue is, at least in Poser 5 the self-collision distance is a constant (and a very small number, besides); it doesn't use the offset and depth settings. But perhaps this has been changed as of Poser 7? Another alternative is to start by posing the garment, perhaps using magnets to get some interesting twists and bends in it, then export that object. Re-import this posed object and run cloth simulation on that.