Got it working with the API they use for the app and web (undocumented APIs are the worst). 
Not sure if there’s a rate limit on the API though, haven’t tested it in HA long enough.
You can download the Python file here and give it a test my changing nodes/6c78fac7-9997-4043-aa24-577595ff6677 to the ID or YOUR thermostat, you can find this by looking through the API, http://www.smartofthehome.com/2016/05/hive-rest-api-v6/ should help you figure some of it out. I know it’s not the best at the moment. :-S
Just drop it into custom_components/climate and add:
- platform: hiveheat
username: [email]
password: [password]
to your config. 
