You have to create a new device template, to interface with it.
You will need the protocol specifications to do this, and the development can be done entirely within the web admin.
Since this is a relatively simple device, the device template can be based on Ruby. (And run inside the Generic Serial Device)... Set the communication type to Ethernet, and make sure you choose the appropriate device category... if you need to, make a manufacturer...
Once you do this, implement ruby codes for the required commands... You can find more information on this in the wiki, search for GSD...an example of an ethernet based GSD device, is the Panasonic IP camera #24. An example of a security panel GSD device, is the Apex 6100.. It's serial based, but the communication method is just the same...you just need to make sure when you create the device from the template, to set the IP and MAC for the device, so that GSD knows where to send data that is passed out the _conn.send() method.