*.info are formatted for Emacs/Mule, not for XEmacs. If you want info
for XEmacs, make it by yourself by 'make info' or 'make jinfo'.

Important variables are EMACS and INFODIR, which are specified the
Makefile in the parent directory. If you format mew.texi in this
directory and/or install *.info from this directory, specify them by
yourself. 

(e.g) make info EMACS=xemacs
(e.g) make install-info INFODIR=/usr/local/info

Note that if you format mew.texi with Emacs 19 or Mule 2.3, delete
@dircategory stuff from mew.texi.