Hacked every mention of "/article.php?story=unixtimestamp&mode=print"
into
/print/unixtimestamp.html

Then created a new folder called print and then created a .htaccess document in this new folder. the Mod_Rewrite rules in this doc are:

RewriteBase /print/
RewriteEngine on
RewriteRule ^(.*).html$ /article.php?story=$1&mode=print [NC,L]