If you go to the trouble of adding the mirror ball (that I dislike BTW) you might as well add a tripod cap of your own. I assume you use a Photoshop "Action" to add the mirror ball? If so, you just need to write an action to add your own tripod cap. (You could possible modify the mirror ball action) if not writing a new action is pretty easy. They are just recorded Photoshop actions (copying your manual steps).