As said before you cannot draw into a model, you can create or copy elements, drawing is something that might be done to a view. Try to be as clear as possible !
Use Jon's advice and copy the element(s) with mdlElmdscr_copy, if you want to copy them to the active model.
You might use to create the copyContext in the calling function and use it as *callbackArg for your callback (might need a typecast)