Sent this info earlier, reposting here in case it is of use for viewing and repackaging an initrd (a cpio+gzip archive):
sudo -s
cd /tmp
# Need a clean directory you can later delete:
mkdir test
cd test
gunzip < /where/ever/it/is/initrd > initrd.cpio
# This does the actual unpack in current directory:
cpio -vid < initrd.cpio
# You can save or delete initrd.cpio here, I just
# delete (otherwise it gets put in any cpio you
# repackage which is not what you want):
mv initrd.cpio ..
# Explore, edit, modify if desired...then repackage
# with new name:
find . -print | cpio -ov > ../initrd-modified.cpio
cd ..
gzip initrd-modified.cpio
mv initrd-modified.cpio initrd-modified
# This is the old unmodified cpio file:
rm initrd.cpio
# Renamed with "-modified" just to keep it from getting mixed up,
# this is now usable as an INITRD entry.
rm -Rf test
exit