For anyone looking for a quick solution for 4.0.18 (and possibly 0.19)
unzip and copy attached to /include/search.php
References for this are....
just the instructions at the bottom of
http://forum.x-cart.com/showpost.php?p=98217&postcount=152
the code from..
http://forum.x-cart.com/showpost.php?p=98220&postcount=153
with the 4.0.18 alteration..
http://forum.x-cart.com/showpost.php?p=128493&postcount=200
Works for me.. not perfect but loads better than standard.
Thanks guys!
xgarb