Open:
/wp-includes/js/quicktags.js
Change/Add/Delete tags to your likening.
233Modifying Quicktags in WordPress
195UIWebView, Changing filenames with Javascript
Calling JS from webViewDidFinishLoading, modifying paths to local. Before that all the images had to be stored into the local path.
http://iphoneincubator.com/blog/windows-views/uiwebview-dynamically-modify-html-documents
Interesting direction, but still looking for an elegant way to mix external sites (HTML) with local content (images, scripts…)