Since the slow cooker by it very nature, creates its own liquid, and scalloped potatoes by their very own nature, create a thick creamy sauce while cooking, the whole idea is not your best one to date. Scalloped potatoes are not inductive to being created in a slow cooker. If you really have to have them, then run to the store and get a box of Betty Crocker Scalloped Potatoes? Did I just really say that?
Illegitimi non carborundum!
I don't want my last words to be, "I wish I had spent more time doing housework"