Anyway this post are some of my thoughts about the topic that applies directly to creativity in other domains and has clear parallels in the writing process and in visual arts. I borrow here from Ken Robinson and define creativity as the process of having original ideas that have value. In the context of education as a process I think that most often creativity is about finding novel solutions to meaningful problems. The problems themselves can be defined by an educator or the learner. When teaching composition, writing or visual arts this definition holds, and one can see how we can ask students to create in a familiar style or form (say painting a still life picture or writing a Haiku) making it uniquely our own by identifying the problem and providing a solution to it. In a sense teaching writing is very much just that. Lucy Calkins coined the phrase "Teach the writer not the writing" (I am actually borrowing it from Evi who is one of the best teachers of writing I know) which I take to mean there is no one uniform way to go through a program, instead as educators we must allow room for learners to define their own problems and find solutions to them. In a way teaching creativity is about teaching our students to identify problems, learn how others solved similar ones and then coming up with their own solution.
This is exactly the reason that I believe there is no universal creativity factor but instead expertise leading to creativity in a specific domain. The process in broad strokes has parallels but the details are often too different. For example I have no capacity to identify problems in [music] composition , but I am extremely capable of doing that in educational research (it is a strange field to be creative in I know).
The area that has the most to offer I think for educators interested in developing the ability to compose is Teaching Writing. You must decipher the parallels of course and the elements that are uniquely linked to writing but I still believe that it is useful.
A place to start might be:
The work of Lucy Calkins, Linda Flower, and unl's own Robert Brooke.