Here is how I solved the problem:
1. I tried several different ways using the gentoo emerge, ebuild and
related tools to reinstall Quills. For various reasons, I wasn't
getting anywhere, so I decided to shortcut the process and install
Quills directly into the zinstance.
2. First, I made a complete backup copy of the
/var/lib/zope/zope-2.7.8 instance.
3. I did an svn checkout of
https://svn.plone.org/svn/collective/Quills/tags/0.8/
4. I created the directory /var/lib/zope/zope-2.7.8/Products/Quills
and copied the svn checkout to that directory (minus the .svn
directory)
5. From the Products directory I changed ownership of the Quills
directory: 'chown -R zope: Quills'
6. I restarted zope and used a browser to successfully access the plone site!
Thought this might be interesting for you.
Kirk