The newer GSM based Kindles all use the AT&T network so it would have to be a AT&T microcell. The problem is that you have to be the owner of the AT&T account to be able to associate it with your microcell. As the owner is Amazon, this means that a microcell won't work. It would be a security risk if you could associate any cell account to your microcell without proof that you own that account because you'd be able to intercept the calls or data.
Unless AT&T and Amazon come up with a new service where they offer microcells, this won't work and also can't be hacked to do so either.