I'm not sure if this is old news or not, but a method I found is having amazon instant video on your phone ready to go, then using the halauncher apk transfer, transfer the amazon app to your android tv/ set it up/ then transfer the instant video app to your android tv and it should work. The interface is not ideal being that it is made for a touch screen, but it is workable.

If there is a better method, please share.