Interesting, to be honest while Anonymous has gotten into so called "hactivism" and vigilante activity recently, that has never really been the nature of the "organization". Anonymous represents the primordial chaos of the internet, and really other than going after those infringing on the territory of The Internet it has little or no real involvement. Indeed it could be argued that at it's core Anonymous is a little more on the side of the rapists here than those wanting to bring them to justice, because they are on the side of hardcore pornography including really shocking stuff and it's distribution, I mean sites where Anonymous hangs out or are connected to them are generally where you'll find some of the most F@cked up and "sexist" crap you've ever seen, with part of the point being that the dark side of the internet is where they hail from.
Don't forget this is the group that pretty much terrorized Jessie Slaughter for being a bit of a twit on the internet, that whole thing with her father "Dong goofed", "cyberpolice", etc... all comes from them watching a little girl through her webcam, which they hacked.
One of the cardinal rules of Anonymous is also that they are not anyone's personal army. If they still hold to those ideals, I'd imagine trying to call Anonymous down on someone like this would wind up with exactly the wrong kind of attention coming to the person making the request. I'd kind of expect Kinsella to have just made himself a target for Anonymous.
As far as the proper way to "appeal to Anonymous" goes, the point is kind of that they are everywhere, specifically on the kinds of forums and image boards where there are no handles, everyone is listed as "Anonymous" which is where the name comes from. Those who care can typically only tell who you are if they pay attention to your address or even go through the trouble of finding out what it is. You pretty much hang out in that community, express your opinion about whomever is irritating you, and it's possible you'll get a raid of sorts going from people with the right skills who agree with you who are Anonymous, however if you come in and go "gee, I want someone to go hack these guys" that's exactly the way you don't do it.... not that I've ever had the interest in doing something like this.
At any rate, we'll see what happens, I'm neither an Anonymous fan or a hater, but I've been aware of them for a while, since before their hacktivism activities got attention. Their actions always seemed to be a mixed bag, but one thing that I believe has always been integral is for nobody to be able to use them as a "tool" or "sic" them on someone no matter how justified. Anonymous by definition stands for nothing, and that includes Justice.
That said it would be kind of cool of a bunch of hackers "got" these kids given the way this story sounds, but I think anyone who tries to appeal to Anonymous sort of misses the point.