Open squid configuration fine c:/squid/etc/squid.conf and add/modify the following.
The following needs to be in that order and I placed it right after the line 'acl CONNECT method CONNECT'.
acl whitelist url_regex -i "C:\squid\etc\url.acl"
http_access allow whitelist
http_access deny all
Then add the htaccess user details to the file C:\squid\etc\url.acl
Finally restart the squid service.