Controlling Pixl menu with D1,D2,D3 ... instead of BTN1,2,3 ... ?

I have created a menu on a Pixl, and this is normally controlled with the small buttons on the card.

I would like, instead, to control this menu with external buttons connected to D1 ... D4.

To understand what the internal events handlers of the menu really do, I tried to replace the setWatch calls by the suggestions of the link Graphical Menu:

setWatch(function() {
  m.move(-1); // up
}, BTN1, {repeat:true,debounce:50,edge:"rising"})­;

setWatch(function() {
  m.move(1); // down
}, BTN4, {repeat:true,debounce:50,edge:"rising"})­;

setWatch(function() {
  m.select(); // select
}, BTN3, {repeat:true,debounce:50,edge:"rising"})­;

It works for a simple menu, but not for editing the value of a number, for example.

So the questions are:

1. Is it possible to reuse the event handlers of the menu (up/down etc...) and call them from another type of event ? (D1 ...)
   
2. Or is there another way to use a menu with different events ?
   
   

Many thanks in advance.