i havent seen the ability to change the SiteWorx theme either on my server or the demo on this site. there are the 3 default themes installed, but can only be changed at the NodeWorx level.
i was thinking this is setup this way so SiteWorx can change the theme incase there is some sort of business logo or something. if this is the case, it would be nice to have a feature in SiteWorx that you can only change to themes that are installed in NodeWorx, but not given the ability to add new ones from SiteWorx