Override CUI.rte.plugins.KeyPlugin

.content.xml

<?xml version="1.0" encoding="UTF-8"?>
<jcr:root xmlns:cq="http://www.day.com/jcr/cq/1.0" xmlns:jcr="http://www.jcp.org/jcr/1.0"
    jcr:primaryType="cq:ClientLibraryFolder"
    categories="rte.coralui2"/>

keypluginoverride.js

function overrideRTEKeyPlugin () {
  // Include the code for KeyPlugin.js and override the necessary functions
}

(function () {
    'use strict';
    var INTERVAL = setInterval(function () {
        if (CUI && CUI.rte && CUI.rte.plugins && CUI.rte.plugins.KeyPlugin) {
            clearInterval(INTERVAL);
            overrideRTEKeyPlugin();            
        }
    }, 250);
}());