Hmmm ... well, I couldn't find out how or if you can create primitives directly in Poser, so I just created one in Rhino and brought it in.

I clothified the ball gown and set to to collide against the sphere, and the simulation has been running for quite a while.  I'll let you know if it does anything.

Will I be able to save the draped ball gown as a separate mesh??

Could be worse, could be raining.