Using 3rd Third Party Themes - The Manual Way to Import
If you leave your 3rd party themes the way they were, Keynote '09 can't seem to handle it and the theme chooser does not open or work properly.
Apple's standard themes are now imbedded in the package contents of Keynote. (if you don't know what that means, don't worry. For those that care opt click show package contents ... Keynote>contents>resources>themes).
You will have to find the third party themes you want to use.
They may be located in the library > application support folder > iWork > Themes or somewhere like that depending upon how you set it up before.
Once you find the themes, I suggest moving them to a place like the desktop or your documents folder.
Once that has been done, Quit Keynote.
Find the theme you want to "import" Double click on it. Keynote '09 should open.
Once it is open, go to File>Save Theme.... you will be presented with the option to name the theme and store it in a folder here HD>Users>Home>Library>Application Support>iWork>Keynote>Themes.
Once you have saved it, quit keynote. Open Keynote and go to the theme chooser. Your new "imported" theme will be at the bottom after all of the Apple standard themes.
Repeat for each theme you want to import.
Hope this helps.
MBPro 15" Unibody 2.8 320 GB/4GB, Mac OS X (10.5.6)