I can't really say anything specific on Susano, because I have no real clue as to what it is. However, I will GUESS that it's a denizen of the spirit world that PROBABLY exists in Naruto. I will also GUESS that Itachi, one way or another, had access to that realm. I'll sharpen that a little. Itachi's sharingan probably gave him access to that realm. Once he came into contact with Susano, he PROBABLY used the sharingan to bind Susano, probably in conjunction with some other jutsu as well.
In other words, Susano is probably not a technique that comes with the Sharingan. Instead, the Sharingan probably made it possible, or at least easier, to bind it. As you can see, there's a lot of guessing going on here. That's because we don't know very much at all about Susano, giving us very little foundation to make predictions. And unless that's one of the techniques Itachi transfered to Naruto, I doubt we'll be getting much more information about it, unfortunately.
edited for spelling