Hello,
You have multiple possibilities here. I suppose, you already have CSS and Javascript code (as well as HTML layout - shown above).
Now you can either amend those pre-defined stuff, to match our CSS List Menu layout. This would be the hardest way.
On the other hand, you can use CSS List Menu and parse its HTML code using RenderedHTML property (discussed in another thread:
http://devnet.kentico.com/Forums.aspx?forumid=36&threadid=7311). Well, for upgrading and hotfixing purposes I recommend that you could
clone this webpart at first.
Third possible way for this aim would be using Repeater webpart, where you can easily define HTML layout as per your needs within transformation. This approach, though, would require using where condition and
custom functions to transformation to achieve the same behavior as in CSS List Menu (I mean especially active item CSS class).
Hope it helps.
Best regards
Ondrej Vasil