Auto-Populate caption data

I have been a happy iPhoto Flickr export user for a long time. Now that I finally have a new machine I stepped up to Aperture. I like to add tites, captions, and keywords locally -- so my local photos can be searched with Spotlight, and then upload everything to flickr. The iPhoto version does a great job of taking my photo title, description, and keyword, and putting them on Flickr. I can't figure out how to make the Flickr export for Aperture automatically populate the description box from my captions, or anything else for that matter.