Try the squidGuard installation from
www.tech-geeks.org. I installed from there and everything worked fine (except the squidGuard configuration panel in server-manager does not work properly in 5.12). You will have to edit trusted and untrusted domains, urls and expressions manually in /usr/local/squidGuard/db trusted (or untrusted). If you want some stations to bypass squidGuard you will have to edit the ipsec file in /home/e-smith/squidguard to add the ip address of stations with unrestricted access. You can use the squidGuard configuration panel to view settings in these files but not change them. They have a very nice setup routine that is really quite simple (download an install file and run it - it goes out and downloads and installs everything you need - just follow the instructions at the end to enter the ip address of your server for the message screen).
I think you can just install this over the other. I have messed mine up once or twice playing with different configuration settings and got things back to where they needed to be by simply reinstalling. You will see messages that some rpms are already installed if you have a previous installation. If you want to uninstall first, uninstall rpms in reverse order and then delete /usr/local/squidGuard and the directories and files beneath it before installing. Don't delete any other directories under /usr/local.
If you want to customize the configuration file be sure to copy any template segments you plan to customize from /etc/e-smith/templates/usr/local/squidGuard/squidGuard.conf to /etc/e-smith/templates-custom/usr/local/squidGuard/squidGuard.conf and edit them there. Expand the template when done.