Add css file to the combiner

Is it possible to add css files to the combiner so it generates 1 big css file in Contao 2.10? I've created this extension a while ago http://www.contao.org/extension-list/vi ... sheet.html and I need it to add css files to the end of the list. Right now I just add the entire html part to the head like the same method Contao 2.9.5 uses.

Hmm, hardly a minute after posting I find Andreas thought of this two weeks ago...
http://dev.contao.org/issues/3161