Hi, Nathaniel. I thank that plaster is easier to work on than drywall. It's a lot harder and thicker. But it does tend to crack when the walls move, which drywall does not. I suggest installing a cut 2x4 for a backer. Check the instructions in my posts of 1/9 and 2/9. The easiest way to find them is to go back to the index page (*** ****'s Message Board), hit Ctrl-f, type the word crown into the box that appears, keep clicking until you come to them.