Livelink xr, tracker and zooming

Hi, i’m experiment with a vive tracker and LiveLinkXR for a virtual studio environment.

So far, so good: the tracker is working perfectly fine. Now, i’m trying to use another tracker rotation to change the focal lenght/zooming of the camera.

I can’t find a way to “bind” the tracker rotation to the FL value of the camera and my understanding of blueprints is almost zero. How can i achieve this?