Hi. Sorry, but I don't see anything in the manual about renaming the inputs. I have an older Pioneer VSX-23 that can do it (as well as some newer receivers that can), so I know what you're talking about. I just couldn't find that in the manual. On my Pioneer, it's under Input Setup, which isn't in the 522 menu system. It's surprising to me, given that the 522 will let you assign names to the radio stations that you store...but apparently not to your input sources.
Do you own one already, or are you just researching?