This is really basic. It’s almost plug’n’play. Go to the mod_pagespeed download page and grab the latest stable version package. Then run `rpm -i mod-pagespeed-stable_current_x86_64.rpm` to install it. It will install a yum repository and all the files and conf needed for mod_pagespeed itself. Then run `service httpd graceful` to restart Apache HTTPd.
Now, open your browser and, before you do anything, open the network console. Then visit one your web pages. The first request will look normal. Pagespeed is analyzing the request the first time. This’ll happen every time you restart httpd I believe.
One last thing. When developing you’ll often want to clear Pagespeed’s cache of files or else your changed files won’t appear for you. Here’s how: run `touch /var/cache/pagespeed/cache.flush`.
Good luck! Hope you love the change as much as I did!