I have the remote and was reading about adding a supplemental single or dual footswitch. I have one of these laying around so I tried it.
https://www.ebay.com/itm/323219590918
It will turn the slot on but I have to push it twice to turn it off. Been looking up info to see what switches but cannot find any info. It would be nice to make this work as it has an LED for on/off. I also have a Beat Buddy with footswitch and that worked perfectly. It doesn't have an LED but it does turn on and off with a push.