They have mentioned a closing date on Face Book Mellow, although I would assume they must have some way of processing late regos, as I'm sure you won't be the only one. I for one haven't registered yet, as I'm still not sure if I can get there.
They are mainly running the event through FB, so if you're not on that I'd suggest sending Old Fart a PM, as I don't think they check here on a daily basis.
Newie