If you are reluctant to use RadioThermostat cloud service, a more simple alternative to ConnectBot + SSHD is to use AutomationManager with the Wifi Radio Thermostat Client + Hub/Server for secure access.
When using the Wifi Radio Thermostat app as a server on the same dedicated android device as AutomationManager/WemoServer the thermostat controls will appear as devices in the WemoServer that can be used directly or in the rule engine.
The thermostat can then be monitored or controlled remotely using WemoRemote, any web browser, or with automation/rules.