I've also heard the Kaffir lime leaves can be used in place of Chamomile.
Aside from that, as I understand it, the Great White (which i too, love btw) seems to be a standard Belgian Wit, with the addition of "humbolt herbs"
I personally just made a wit with a little bit of chamomile thrown in at the end of the boil.
Seemed to give it a smoother taste IMO.