mkdir /tmp/initramfs cd /tmp/initramfs gunzip -c /boot/initrd.img-2.6.33-1 | cpio -i
Now edit the files
find * | cpio -H newc -o | gzip -c > /boot/initrd.img-2.6.33-1b
Well, you need to edit your grub or lilo config to make use of the new initramfs. I recommend to do it this way and not to overwrite the exiting (working) initramfs.