Hi, first of all, i don't use Pub Jukebox, i use a different software but had similar problems when trying to control a JukeBox in a Pub.
I wanted to be able to adjust volume, Balance (for different zone volume), Mute, skip track and shutdown & add free credits remotely from behind the bar.
I used a program called volume2 (
https://irzyxa.blogspot.com/p/downloads.html) to control the sound side of things, you can send keystoke to volume2 via a numerical keypad (either USB or wireless), i used USB to make the control more robust (no flat batteries).
I made labels for the keypad and put it in an enclosure so you could see only 9 keys (didn't want to confuse bar staff).
Hope this helps,
cheers
Tony