The following is the closest thing I have to Jim Flanagan's zeitcode.pm module.
Jim's Original Instructions are still valid.
What I did was extend the module to take in a file
searchengines.txt that contains a list of known search engines. In the XML or HTML output, it includes only results from the specified referers.
zeitcode.pm also increments a counter in
searchengines.txt associated with each referer it found, as a way of distinguishing active referers from obsolete ones.
Finally, it writes a new file,
searchengines.new.txt, with suggestions for new referers that might be from search engines. This file is meant to be reviewed by a human, and for certain referers to be manually added to