<
URL:http://bittersweet.sysc.pdx.edu/doc/emacsen-common/> may also be
of interest. This is a pre-xemacs21 way of dealing with installing
Lisp for multiple emacs versions. The lisp is byte-compiled at
installation time.
The source is available via debian.org... it's a 20 minute read at
most; probably less time than that for most of you.