 <p>In addition to what @abarnert said, I today had to find out that the default <code>cpio</code> utility on Mountain Lion uses a different archive format per default (not sure which), even with the man page stating it would use the old cpio/odc format. So, if anyone stumbles upon the <code>cpio read error: bad file format</code> message while trying to install his/her manipulated packages, be sure to include the format in the re-pack step:</p> <pre><code>find ./Foo.app | cpio -o --format odc | gzip -c &gt; Payload </code></pre>