The race is full, so no on site registration will be available. Someone mentioned there may be some charity slots available, but I'm not sure exactly what that means or if it's true. I'm sure the race director Rob will chime in sometime soon once he gets through his paperwork and Snotcycle logistics.
Also, put the word out through your cycling network, there are always people who have to bail on the race because of unforeseen circumstances. If they know you are looking for a slot, you can make a deal w/ them.