How do I make an installation initrd.img for a new kernal?

[Brad Bonkoski]

man mkinitrd
-B

Barry Scott wrote:
> I need up update the newwork install for FC4 so that it
> supports new hardware (nVidia ethernet - forcedeth).
>
> The 2.6.17 kernel is fine in this case. But the initrd.gz that
> is installed in /boot is nothing like the images/pxeboot/initrd.img
> from the installation CD.
>
> I need to know how the images/pxeboot/initrd.img  was made
> so that I can make a new one for the 2.6.17 kernel.
>
> Can anyone point in the right direction?
>
> Barry
>