How do i add a custom tab to a facebook "application profile"?

When creating an application an application profile tab is provide with the application... How can i add a custom tab to this page? Is this just not possible?

The settings of such a ta开发者_如何学编程b are different then the settings on a normal fan-page? also facebook documentation is very meager about this subject...

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It looks like Facebook changed it recently (October 2011). In the past I used to add custom tabs to app profile pages without any trouble, but now I can only add custom tabs to fan pages. I had to use a 3rd party iframe app provider (Involver) to achieve this. I am still looking for an alternative solution since these services are a bit expensive.