Adding a Fill Box
You should be able to create a fill box in your score. For example, in Billy Joel's song Allentown, there is a fill box which is isolated in a box at the bottom of the page.[http://paperzz.com/doc/847193/the-billy-joel-keyboard-book.pdf---arnes](bottom of page 5)
Comments
You can do this already. Just create the music you want in that box (perhaps in another score) then use the Image Capture mode to copy a picture of it to your clipboard, then paste in into a frame in your main score.