Need help to create netboot image for EL6 kernel

We use netboot to boot our RedHat Linux kernels. We usually use mknbi tool to create netboot image from Red Hat Linux kernel. However, I can't get this to work with the new Red Hat EL6 kernel.

One online document I found seems to say mknbi should not be used for Linux 2.6 or newer kernels any more, and wraplinux must be used. I downloaded wraplinux. However, I can't get this to work either. I can't find a clear document online to tell me how to use wraplinux to create a netboot image. I don't know what went wrong here.

I have been looking into this for quite a while. Please help if you can.

Have you looked at https://partner-bugzilla.redhat.com/show_bug.cgi?id=607544?