Some badly js will work ?
setInterval(function () {
if (!document.getElementById("button10000111")) {
$('.TextEditor-controls').append('<li id="button10000111" style="float: right;"><a href="https://my.url.com" target="_blank"><div class="Button hasIcon"><i class="icon fa fa-fw fa-exclamation-triangle Button-icon"></i><span class="Button-label">Rules</span></div></a></li>');
}
}, 500);
Well making extension is the best but if you cant... ?