I've seen that some people can post ACE paces and score keys but I cannot figure out how to do this. There is no ISBN number. Can anyone help?

I believe you would need to post them individually as books without an isbn.  Or you would do a search for "all books" to see if someone has posted them in the past and that may save you some time.  

Which grades of paces and score keys do you have?

They're posting them as an item without an ISBN.  The system then gives the items an auto-generated "fake" ISBN.  It will take some time to post them all that way.  What I would do in your shoes is offer them in the deals/promo sticky thread as a set - one for each level or course.  Then you might find a home for a bunch at once, and you won't have to go through all the adding info work.