[CentOS] Adding a kernel module to the ISO/installer initrd?

Tim Nelson wrote:
> Surely someone has rebuilt the initrd for the installer ISO? I recall seeing something on the list about it previously in regards to storage controllers but I cannot seem to find it now...
> 
> Is there somewhere I can look to see the original mkinitrd command used to build the initrd on the ISO? I could then ensure I have all of the modules specified there along with my additional module.

I've tweaked distributions' initrd files by doing

gunzip -c --suffix '.img' /boot/initrd-<version>.img | cpio -i

to unpack the file, and

find . -print | cpio -c -o | gzip -c9 >/path/of/new/initrd

after making changes.

Jim