Got it. Glad you posted this again as I had posted this configuration and a non-standard one. This one is a standard power to the light in the middle so there is a solution.
There are a couple options depending on which box you want the switch in. Take a look at this thread starting at my post. Also scroll down. How you do it depends upon which box has the non-neutral hot and which box you want the Inovelli in. You will need to use an Aux in the other.
This should get you started, but post back with questions.