If your question really was "how" to get it done I've tried OnlyWire (which I would not suggest) and will be trying out socialmarker.com in the near future.
You sign up for the accounts ahead of time (not unlike the list of individual ones you've been given), and then socialmarker walks you through site by site allowing you to pick and choose the best place(s) to post any particular post.
With OnlyWire, it works the same way in a one-page, supposedly one click submission format, but we have our (huge) doubts whether anything sticks (Simpy appears to be the only one on their list that gets it over time).
Hope this helps
