[CentOS] Hidden networking device configuration

I am trying to configure load balancing for a couple of CentOS4 servers. In order to make it work, I need to add a hidden networking device on each server with the virtual IP. I found the following instructions on linuxvirtualserver.org for doing this, but they don't work.

echo 1 > /proc/sys/net/ipv4/ip_forward ifconfig dummy0 0.0.0.0 up echo 1 > /proc/sys/net/ipv4/conf/all/hidden echo 1 > /proc/sys/net/ipv4/conf/dummy0/hidden ifconfig dummy0:0 172.26.20.110 up

When I try to write to /proc/sys/net/ipv4/conf/all/hidden, the system refuses to let me create the file. I'm logged in as root, so why am I having permission problems?

Also, I believe these instructions are for 2.2 or 2.4 kernels. Have things changed with 2.6?