For mega menu for wordpress situation a little complicated
At the the beginning i planned to do it about same as for Joomla! one(it’s succesfull, but not still easy to manage) IE to use existing menu and add options to it but But for wordpress i had found more options – It’s very easier than Joomla! – as all links for menu can be only posit item, taxonomies, or custom link
Not sure eveyone understands it – but who know will undersand
PHP-JS Developer of Joomla and WordPress.