How to replace an element with a div (and vice versa)

Hello there,

I'm trying to replace an element (<plugin></plugin>) completely by another element (<div>).
I use dataFilter to catch the plugin element but can't make it any further.
Is there a working example somewhere?
I use

var element = new CKEDITOR.dom.element('div', editor.document );

To create the div and fill it with content by using

element.setHTML(html);

It works this far. I tried to use the CKEditor method

element.replace(oldElement);

But this will fail silently.

Any help is appreciated, this has to be something someone did before..