I had complied my own custom PHP because I need to have iconv() extension enable. But my customed PHP seens does not recogonize the ZendOptimizer. I e-mailed support, they told me I need to install one for myself. I had trouble install it since I does not have root account access and I don't know the command to have it just install on my account.
This is the command I use:
tar xvzf ZendOptimizer-2.1.0b-Linux_glibc21-i386.tar.gz