There are two main flavors of packages.
XEmacs Lisp packages are distributed in two ways, depending on the intended use. Binary Packages are for installers and end-users that can be installed directly into an XEmacs package directory. Source Packages are for developers and include all files necessary for rebuilding bytecompiled lisp and creating tarballs for distribution.
Binary packages may be installed directly into an XEmacs package hierarchy.
Source packages contain all of the Package author’s (where appropriate in regular packages) source code plus all of the files necessary to build distribution tarballs (Unix Tar format files, gzipped for space savings).
Currently, source packages are only available via CVS. See http://cvs.xemacs.org/ for details.