to make it a toggeling switch should be possible but needs investigation and probably is not possible passive, which means that you also have to extract supply from the box or build a little pcb into the box…
Perhaps I don't understand the point here, but why wouldn't it be possible to turn it into a toggling switch?
The switch is obviously momentary, and if you hold it, it does record/overdub as long as you hold it, so replacing the switch with a latching one should make record/overdub latching, or am I missing something?
(fyi: the reason it's made that way is that the same switch is also used for tap tempo, meaning short press = tap, long press = record/overdub (sus)).