Edit: I forgot to warn you that several hundred people will add you to their circles, and you will get notifications when that happens. You should probably go to https://www.google.com/settings/plus and preemptively disable those notifications before you are drowning in them.
That's all you need to do to get the results mentioned in the article, but you might get a lot of unwanted noise in your Google+ stream from this circle. If that's a problem for you, go to your Google+ "home" page https://plus.google.com/stream and find your new HN circle in the left-hand column. When you click it, you get a stream made from that circle, and you can change the "volume" of the circle using the slider that appears in the upper-right. Now when you browse your normal stream you won't get noise from the HN circle.