The option does not exist on Xerox products (AltaLink, Connectkey, Discovery, Endeavor excetera)
It does exist on FujiXerox and VersaLink (You 53XX is Fuji-Xerox)
You would need to call Xerox and submit a FER (Feature Enhancement Request)
I am trying to find where I can enter the authentication information for the proxy server on a AltaLink C8055.
I have been able to enter the IP Address of my proxy server, but on this model I cannot find where to enter a username and password so the device can authenticate. On my older model WC53XX models this is simple.