Recent changes in quinn's repos have moved themes to a different window decorator called cgwd. cgwd provides the same functionality as gnome-window-decorator but adds the ability to theme. The packages we need are cgwd and cgwd-themes (there are more packages but these two take care of all the dependencies).
To be able to theme your compiz you will need:
cgwd
cgwd-themes
To start cgwd instead of gnome-window-decorator:
In the scripts or session modifcations you have made in earlier parts of the walkthrough, change gnome-window-decorator to cgwd. To apply themes run gcompizthemer either from your preferences menu or from a terminal. Also please note cgwd uses an .ini file, not the gconf keys used by gnome-window-decorator, so you must use gcompizthemer to apply themes as setting gconf keys will not work.