A simple solution is to use Keynote with a chromakey green background. Learned this from Alex Lindsay from Pixel Corp. You can build it in FCP/AE with animation then export it as QT and drop it in Keynote(if you can produce it in advance or simply create the template in Keynote and make text changes on the fly using different pages for each graphic/Lower third. Easy and it works with the keyer function of that switcher.