set admin auth remote unknown keyword remote

I'd like to be able to log into the web portal with admin permissions, but when I connect to the console and try the command:

set admin auth remote

It returns unknown keyword remote. the documentation implies that this is the correct command to allow read-write permissions remotely. Ultimately, I'm trying to be able to manage administrator accounts remotely. What am I missing? Thanks.

SSG-320M

NetOS 6.3.0r17