Globally install a signed add-on
<p>Is there any way to <a href="http://kb.mozillazine.org/Installing_extensions#Global_installation" rel="nofollow noreferrer">globally install</a> a signed addon (extension)?</p>

<ul>
<li>copying the file to the installation directory did not do anything</li>
<li>starting Firefox as the owning user of <code>/usr/lib/firefox-addons/extensions/</code> did not work (I set the group id to mine and did a <code>chgrp 775</code>).</li>
<li>I had previously offered a bounty on <a href="https://stackoverflow.com/questions/12251625/installing-firefox-extension-for-all-users-system-wide-installation">Installing firefox extension for all users [system wide installation]</a>, but to no avail. That contains the old procedure that worked.</li>
</ul>

<p>When you unpack the <code>.xpi</code>-file, the signatures do not match the unpacked files.</p>

<p>Any ideas?</p>