Well Thomas, not easily.
I see on page 27 of the XB-14 MK2 User Guide ( https://www.allen-heath.com/media/XB-14MK2+User+Guide+AP8769_2.pdf) that there is the remote B D-Type with an "open collector" for each stereo channel start.
However, it isn't simple to get this into PlayIt Live.
The remote start Plugin ( https://www.playitsoftware.com/Plugins/View/RemoteStart ) will take MIDI (and works well with a MIDI pad) but that's not what your mixer produces.
I've not tried it myself (although I'm interested in doing so hence I did some research) but this looks the most promising product available:
The website suggests that "custom" products are available and I would drop them a line explaining that you want to turn mixer start GPIOs into MIDI commands and see if you can get a "special".
It's a rather nicer solution than trying to emulate keyboard key presses
If you do get this working I would be interested in hearing about it.
I have Allen & Heath XBS 14. The desk apparently has a start/stop cue feature. Is there anyway `s I press the 'on' button to start what is on the layout log in Playit live.