Recently I installed SwitchiFy at two places in my house with the help of our electrician. Here are the photos taken during the process:

Opening up the switch box. The box is about 8 inch X 3 inch and about 4 inch in depth.

The 3-Way switch used for the lighting. The centre terminal is Live wire and the other two terminal connects to the terminals of the other 3-way switch.

Connecting SwitchiFy to a 3-Way switch is very simple. The two wires in the above picture will go to the Outgoing terminal in the SwitchiFy and the Incoming terminal in the SwitchiFy should be connected to the two terminals of the 3-Way switch (like shown in the below picture). 

SwitchiFy needs a 220V or 110V power. So we tapped it from the existing line:

After the wiring is done:

As you can see, SwithciFy fits nicely into an existing switch box. We used a two way tape to adhere the board to the casing and isolate it.