I have a plain install of centos, with no control panel.
I was trying to add zend optimizer using yum.
Searched online and said some people used:
yum install php-zend-optimizer

But when I run that it says no packages are available.
I also tried to search for just php-zend* and no packages are shown.

I found this page with instructions for adding a repository that has zend apparently:
http://support.34sp.com/KB/a160/zend...d-ioncube.aspx

but it mentions "plesk" - so not sure if it's safe to use on a non-plesk system.

Thanks for the tips!

Well fortunatly I found the answer to my own question . Posting it here in case someone else searches for it.
I had to add the RPMforge repository to YUM, with Yum priorities plugin installed.
You can follow the instructions here to do that in centos:
http://wiki.centos.org/AdditionalRes...ies%2FRPMForge

After I followed those instructions I could then just type:
yum install php-zend-optimizer php-ioncube-loader

To install both zend optimizer and ioncube loader.

Then, just reset apache:
cd /etc/rc.d/init.d
./httpd restart

Now go to a test phpinfo page and you will see the zend engine credits, mentioning both optimizer and ioncube loader installed.