XEmacs support in Gentoo is currently less than stellar due to lack of a maintainer. Looking at some of the ebuilds this situations has been going on for some time. Some of the XEmacs lisp packages have not been updated since 2003 and there are a bunch of bugs open for XEmacs-related issues.
I’m not sure I would like to become a maintainer for XEmacs in Gentoo. The process of becoming a Gentoo developer seems a bit convoluted and unclear, and I am also not sure that I can bring the commitment to do this for some time. But having a need for some of the updated packages and hating to see my efforts only being useful for myself I set up an overlay for updated XEmacs stuff. It can be accessed at
http://moving-innovations.com/svn/xemacs. So far I have only added the packages that I have installed myself. Maybe, if things work out well, I’ll also include other packages and an updated xemacs itself. Let me know if you think this is useful or if you have specific requests.