The ISS cannot be changed, but the console can.
As John says though, it is unofficial, at the users risk, and will invalidate any warranty you may have. I wouldn't do it if you are not technically competent either, but you just have to send some commands via a terminal emulator then power cycle the console. And then blame yourself if you "brick" the console.
Having said that I converted one of my consoles from US to EU frequency without any issue.