Hey Nick,
Regretfully this isn’t a feature offered by X. It could be possible with custom development, but this would be outside the scope of support we can offer. You may wish to consult a developer to assist you with this. X is quite extensible with child themes, so there are plenty of possibilities.
Alternatively, you might also want to use Ubermenu plugin which comes bundled with X. See http://wpmegamenu.com/ for more details.
Thanks for understanding. Take care!