You need to implement the Alexa Skill Kit java source to do so.
But you need a Amazon AWS Account with a valid creditcard saved....
I don´t think there is one.
I´m just doing it (for b4a; work in progress) but i stuck because i do not have a AWS Account with Creditcard. So i cannot get a valid app id in my amazon account....
found a Home Automation Bridge that works fine. https://github.com/bwssytems/ha-bridge
devices are directly found by alexa, without any skill activated and controls them by sending "Posts" like ifttt but in the local Network
not really what i wanted, but a nice Workaround