Adding driver to Imaging CD

Can some kind soul fill in the bit I've missed. I'm using Zen 7.1 SP1 with
ir1 applied.
My kernel version on my compile machine matches my imaging cd kernal.
Ive compiled my driver.
I've unzipped and un cpio'd my initrd from my imaging cd
Ive added the module.ko to /lib/modules/2.6.46-override-default/initrd
Ive re cpio'd the initrd and rezipped it
removed the gz extension
Replaced the original initrd on my ISO image
Burned a new ISO

Still when I boot the pc off the cd, it doesn't recognise the presence of
the new r8101.ko in the initrd on the cd. What have I missed? How do I
tell the boot process to look for the r8101.ko at boot? Is it an insmod
and if so at what stage? I'd like to get this right so I can contribute
the driver back.

Getting increasingly frustrated,

Pete