I don't know if you can get to it without Poser 5...it is one of the "rooms" offered as part of the package:

Content Paradise
Poser 5s Content Room hosts Content Paradise, your portal to the vast virtual world of Poser add-on content. Content Paradise lets you easily search, purchase, and download third-party content from the Web without ever leaving Poser! A simple and intuitive user interface makes the process efficient and easy. And Poser 5s Download Manager can automatically detect and install many types of content!
http://www.curiouslabs.com/article/articleview/237/1/48/?nf=1

Of course it hasn't been accessible before so what it actually has in it is unknown to me.