So it sounds like you understand the port limitation on the expander and that you'll need to use the second connector on the 9260 to directly connect to 4 of the drives in the 4U JBOD. I'm having a hard time following where the disconnect is at this point so I though I would make a very very ugly paint diagram of what I think you need to do. If that doesn't make sense or doesn't match what you actually have it might at least give us something to refer to.
Hope this helps.
Edit: Image isn't working for me at least so the URL is http://i.imgur.com/DCHoFIt.jpg
Hope this helps.
Edit: Image isn't working for me at least so the URL is http://i.imgur.com/DCHoFIt.jpg