Someone posted a link in comments on the article on WPCentral on how to get it on your phone. I clicked it on my computer, but said I needed to download it on my phone. Long story short, you need to click the link itself on your phone, searching in the app store won't do it. I did so, it brought up the app perfectly, saw that it was a Nokia app and downloaded it. When it downloads, it appears in the app list as it downloads, but then it will disappear. If you go to your settings menu, you will then see the Accessories setting added.
Feel free to read through the article on the main page, but if you want the link, here it is
accessories | Windows Phone Apps+Games Store (United States)