The easiest way to install lshw on a RedHat based system is to get the package from DAG:
http://dag.wieers.com/packages/lshw/
If you already have the DAG repository in your sources, just use
up2date lshw
or
yum install lshw
based on what package management tool you are using.
If not, just download the appropriate package for your operating system (for centos use the appropriate rhel base version) and install it manually with rpm. For example on a Centos4 i386 system I would use:
