The package was renamed in Portage, please update the documentation, trivial one-liner fix sed -i -e 's:x11-terms/terminal:x11-terms/xfce4-terminal:' <file> http://www.gentoo.org/doc/en/xfce-config.xml
Thanks; applied.
missed some; i fixed the Terminal references in openbox.xml and utf-8.xml. grep is your friend! :D