I thought it might help if I explained my aims a little more completely. I'm 3,000 miles away from those who I'm going to be trying to help. They are users, not tinkerers. I do not have a Kindle Fire to experiment on.
I'd like them to be able to take the Kindle Fire out of the box and turn it on, then sideload the mobi files I provide them and be able to open and read them like they just bought them from the Kindle store.
Can it be done? Could someone tell me how to coach them to do that?