Adding rich text / tinymce to module?

// Get access to template variable function (to output the RTE)
			include_once($modx->config['base_path'].'manager/includes/tmplvars.inc.php');
		  
			$event_output = $modx->invokeEvent("OnRichTextEditorInit", array('editor'=>$modx->config['which_editor'], 'elements'=>array('tvmailMessage')));
		
			if(is_array($event_output)) {
				$editor_html = implode("",$event_output);
			}
			
			// Get HTML for the textarea, last parameters are default_value, elements, value
			$rte_html = renderFormElement('richtext', 'mailMessage', '', '', $newsletter);
			
			echo $rte_html;
			
			echo $editor_html;