BuddyPress.org

“incorporate an article/post slideshow into the Thematic theme”
Getting the slideshow to work is more on the WordPress side … if you’re making a slideshow of the posts/articles in your site. BuddyPress doesn’t have anything to do with the slideshow … unless you’re making a slideshow of BP Gallery images or members or groups, etc.

Furthermore, since you’re using the Thematic theme (which has a BuddyPress-compatible version/adaptation), might I point you to the Thematic Forums since they can assist you better in choosing best slideshow/plugin for your site http://themeshaper.com/forums/