Simply installing the Xkey Plus program on Windows, connecting the Xkey Air 37 via USB and checking for the bluetooth update in Bluetooth Firmware under Bluetooth tab in Xkey Plus. The device was on a somewhat older version of the Bluetooth Firmware. The new firmware connects to the iPhone 11.
After some heavy modding of my setup I have replaced the iPhone 5s Model D with an iPhone 11 Model D
Just made a pretty short video of the new installation and uploaded it to youtube:
