Thread:Skin talk:Chameleon/How to extend Chameleon

I'm currently deploying MediaWiki for a custom book project. I would like to use Chameleon as a basis-skin, but I need to comply with an already existing layout. I'm aware of having a custom layout XML-file, but I would need to change some of the HTML output. (e.g. footer/articel tag, order of divs, etc.) What's the preferred way of extending this skin? Are there any custom hooks or do I need to fork (wich I would like to avoid)? Help is appreciated.