Merging iPhoto library into Aperture in the new Aperture 3.3?

Having trouble merging my (one) iPhoto library into Aperture. The idea is to merge both the iPhoto library and the Aperture library into a "single, unified Aperture library" that iPhoto can also read (new feature as of Aperture 3.3 and iPhoto 9.3).

The tech note for doing it is here:

Aperture 3.3: How to use Aperture to merge iPhoto libraries

http://support.apple.com/kb/HT5296

Summary

If you have Aperture 3.3 or later and iPhoto 9.3 or later, you can use Aperture to merge multiple iPhoto libraries together to create a single unified library with all your photos. You can then continue to use the unified library in both iPhoto and Aperture.

To merge the libraries:

1. Open Aperture 3.3 or later.
2. Click the File menu and choose Library > Switch to Library > Other/New. Use the library selector to choose one of the iPhoto libraries you'd like to merge.
3. Choose File > Import > Library
4. Select one of the remaining iPhoto libraries you wish to merge.
5. Repeat steps 3-4 for each additional iPhoto library you wish to merge.

I've followed steps 1 & 2 (BTW I had already opened the iPhoto library in 9.3 and closed it as recommended), but step 3 - when I "Choose File > Import > Library," I just get a standard open file dialog, and the iPhoto library is grayed out. Not too surprising, considering that this is the library that's already open in Aperture.

So, import is not possible.

Anybody done this? It appears to me that the documentation is faulty...