I recently asked this same question of Course Manager support and this is the response I received:
Please know that multiple teachers can collaborate on an iTunes U course, all they have to do to accomplish this is share the Apple ID that was used to create the first course. In case an Apple ID hasn't been created, I would very much recommend to use a generic email as your Apple ID.
As far as transferring an existing course to a different teacher, I would rather recommend to recreate the course. You can find more information about recreating a course below:
Please let me know if this will work for you or if you have further questions, I'd be glad to help!
So the answer is "No," you cannot do this currently. In fact, even if you do go the route of sharing an AppleID, only 1 user at a time can be signed in to Course Manager.
I have heard it through the grapevine that Apple is working on adding the ability to collaborate in an iTunes U update to be released in the Spring.