The Venstar Colortouch, as of version 3.08 of their firmware (announced Jan 22, 2014) , uses a RESTful API. This can be enabled on the Thermostat device itself, by enabling the “Local API” option (Menu->Accessories->Local API). You must buy the separate WiFi adapter to use (SkyPort).
All Pytomation needs to know is the Thermostat's “IP Address”, which can be found using the “Accessory Info” option (Menu->Accessories->Accessory Info).
Using in an Instance