You cannot install openerp from centos repositories using yum and the only way to do that is getting the source code and compiling it. Since you are using and old OS, you need to upgrade your gcc and other packages.

First of all you need to install the dependencies, then get the source code from openerp's official web site and after that, you must compile the source code.The following script does all the tasks for you (don't forget to run as the root) :

http : // forum . openerp . com / forum / topic36094.html