i am not positive what you mean by "get the characters to exist on the 'real' cover", but i love how this looks, anyway!
maybe you are talking about the 3 dudes in the middle and how they seem to float over the notebook cover. perhaps you want them to appear flatter(?) on there or something. not sure...
however, the believability of this cover blows me away. its so nicely beat up and i love the middle-school-style 3d effect drawn in on the title! bonus points for getting the meade look right on for the credit/page text!