try this code in a loaded js file:

odoo.define('web.aek_shortcuts', function (require) {
"use strict";

    var core = require('web.core');
    var form_widgets = require('web.form_widgets');
    var FieldOne2Many = core.form_widget_registry.get('one2many');

    var _t = core._t;
    var QWeb = core.qweb;

    var ctrl_count = 0;
    $.ctrl_bind = function(key, namespace, callback, args) {
        var ev = 'keydown.'+namespace;
        $(document).on(ev, function(e) {
            if(!args) args=[]; // IE barks when args is null
            console.log(e.keyCode)
            if((e.keyCode == key.charCodeAt(0) || e.keyCode == key) && e.ctrlKey) {
                callback.apply(this, args);
                return false;
            }
        });
    };

    $.ctrl_unbind = function(name) {
        var ev = 'keydown.'+name;
        $(document).off(ev);
    };

    FieldOne2Many.include({
        init: function() {
            var self = this;
            this._super.apply(this, arguments);
            var context = this.dataset.context.eval();
            if(context.shortcut != undefined){
            	ctrl_count++;
            	self.ctrl_count = ctrl_count;
                $.ctrl_bind(context.shortcut, this.ctrl_count, function() {
                    self.viewmanager.active_view.controller.do_add_record();
                });
            }
        },
        destroy: function() {
            $.ctrl_unbind(this.ctrl_count);
            this._super.apply(this, arguments);
        },
    });
});

It may require more extensions but this is the first draft