Add this plugin to either a layout or an individual tile. Controlling the plugin requires you to send UDP data to the running info-beamer process on port 4444. You can send
root/plugin/cover/alpha:1,1
The first value is the opaqueness of the overlay with 1 being completely black while 0 is transparent. The second value sets the duration of the change in seconds. The above sets the screen to black within one second.
Similarly the following removes the black overlay and shows your content again in 2 seconds.
root/plugin/cover/alpha:0,2