AFAIK you can't export or import users on the 53XX machines, but if you could it would be in exactly the same place you exported it from in the first place.
If you had a printer that has the feature, it would be here like it is on the 57XX
But it doesn't exist in any 53XX device I have seen
The only thing you can certainly import is Address book entries, but that is just email/fax stuff, not users per se.
