To add a static route to modern RedHat distributions you need to do the following:

Assuming you want to add a route to the network via the eth0 network interface to the gateway at 172.16.254 you would create a file called /etc/sysconfig/network-scripts/route-eth0 and in that file put the route: via

Either ifdown and ifup the interfaces or reboot to see the changes.

Of course you could just add the route manually until the next boot:

route add -net netmask gw dev eth1