I am pretty sure that the integration described there does not work anymore with the latest versions OJS or Wordpress. Definitely not with OJS3.
There was some work done last Fall with an OJS Rest API which could be used to create such integration (of course not directly, but it would be a basis for it).
@asmecher knows best what the situation is with REST? (because I am interested as well :D)
Thanks, I am currently not doing any integration between OJS and WP but would have some other plans for the REST when it is ready. The problem with RSS is that you are usually stuck with a list of latest articles whereas with REST you can define what you need yourself.