Install on the pc the firefox addon called user agent switcher.
In 'options' create new one named Nokia N900.
Copy in the description of the user agent the lines you find in a thread of this forum teaching about n900 user agent.
Then in firefox select the new user agent.
You have to make believe to OVI that you are using your phone.
Integrate this post with the youtube tutorials you can find searching by google 'how download ovi pc'.