Keep squid and all that mine configuration in place. Then configure squidGuard from within your squid.conf file.
Get a one time free download of a black list here.
http://urlblacklist.com/
Setup squidGuard to use the black lists.
http://www.squidguard.org/Doc/install.html
Then use the tested squidGuard in squid configs.
gedit /etc/squid/squid.conf
In the section: url_rewrite_program
redirect_program /usr/local/bin/squidGuard -c /usr/local/squidGuard/squidGuard.conf