Howtoforge published a tutorial about installing OpenVZ on CentOS 5.7

In this HowTo I will describe how to prepare a CentOS 5.7 server for OpenVZ. With OpenVZ you can create multiple Virtual Private Servers (VPS) on the same hardware, similar to Xen and the Linux Vserver project. OpenVZ is the open-source branch of Virtuozzo, a commercial virtualization solution used by many providers that offer virtual servers. The OpenVZ kernel patch is licensed under the GPL license, and the user-level tools are under the QPL license.

  Installing And Using OpenVZ On CentOS 5.7