How do you 'join' Oneworld?
 

When accessing the Oneworld 'round the world' itinerary planner, you are prompted for your email address and password. When you are declined, for not having an account, there is no where to go to learn how to get one. All the contact information takes you to the member airline sites. None of my frequent flyer account passwords work there.

Does anyone know how to become a member of Oneworld? Or just access the RTW ticketing tool?

The email address and password the planner asks for is only there so that you can save itineraries as you are planning them. It is not related in any way to any airline or program. You only need an account if you have or want to save itineraries.

You can access the planner without having an account or saved itineraries on oneworld.com. Just click on the "Plan and Book a Round-the-World Itinerary" or "Plan a Multi-city itinerary" links and use the tool. If you then want to save your planning, it will ask you to log in or create an account.