It's possible. Get there first thing, I'd suggest about 30 minutes before the desk at FCL opens. They have a number of slots for 'on the day issues' which get assigned in order of arriving there. Make absolutely sure you have all required paperwork with you, because if not they won't even allocate you a slot while you run around trying to get it all together.
As far as I know they will only do this for additional ratings and the like, but never for initial licence issue.