Is it possible to add a button directly with javascript ?

I'm trying something like this on jQuery.ready() function because I don't want modify ckeditor folder structure

So I'd like to add 'live' a plugin to CKEDITOR. Is it possible ?

 

CKEDITOR.plugins.add( 'timestamp', {
    // icons: 'timestamp',
    init: function( editor ) {
        editor.addCommand( 'insertTimestamp', {
            exec: function( editor ) {
                var now = new Date();
                editor.insertHtml( 'The current date and time is: <em>' + now.toString() + '</em>' );
            }
        });
        editor.ui.addButton( 'Timestamp', {
            label: 'Insert Timestamp',
            command: 'insertTimestamp',
            toolbar: 'insert'
        });
    }
});