The Amazon Fire TV has disabled the option to "Install from Unknown Sources" -- so is there another way to turn it on? You can still sideload apps using ADB but this setting needs to be enabled to install apps directly from the device (for instance if you want to install a dev build via HockeyApp)
Any ideas?
Amazon just released a testing service for Android apps called "Live App Testing". It solves the problem I posed this question for since it allows you to distribute apps to testers without them having to use ADB to install apks manually: