I haven't seen anyone do this but we do offer the admin the ability to upload a guest file to the controller. I would create a test user in that screen Thomas suggested, then use that to create new accounts and upload them to the controller....
The following example imports the previously exported file created by the export_clients command in the controllers CLI (SSH):
EWC.extremenetworks.com:wlans:clients# import_clients 192.168.4.1 admin /support clients_export_file Please input password: Attempting to download file...
(Requires Exrtranet Log In) - Page 22 - import_clients -
https://extranet.extremenetworks.com/downloads/Pages/dms.ashx?download=03a845cf-b879-4ffb-b2b2-9cc70...
Doug Hyde
Director, Technical Support / Extreme Networks