I'm not sure that there's a lot to say. apache2-mode.el is one file that can be downloaded and installed into the XEmacs load-path. Code like this in ~/.xemacs/init.el should make everything work:
   (autoload 'apache2-mode "apache2-mode")
   (add-to-list 'auto-mode-alist '("httpd.*\\.conf$" . apache2-mode))
If it is necessary, a proxy (for the w3 package) can be configured like this:
   (setq url-proxy-services '(("http" . "proxy.example.com:3128")
                              ("no_proxy" . ".*\.example\.com"))
This code works fine with Apache 2.0 and appears to work with the Apache 2.2 documentation as well. M-x customize <ret> apache2 <ret> will let you tweak the configuration as you see fit.

If there's a set of keywords that you'd like to see included by default, feel free to send me the list and I'd be happy to update the code to include them if they're of general interest. Site specific directives can be customized, see above. Presently I only include mod_perl and mod_python directives because that's the majority of extensions that I use.

Any comments or suggestions should be addressed to montuori@gmail.com.

Download apache2-mode.el now.