As to at least do some progress in the integrity part of Gentoo Hardened (a subproject I'd like to extend towards greater heights), I dediced to write up a small guide on how to work with AIDE. The tool is simple enough (and it allowed me to test its SELinux policy module a bit) so you'll get by fairly quickly.
However, what I'd like to know a bit more about is on how to use AIDE on a hypervisor level, scanning through the file systems of the guests, without needing in-guest daemons. I wrote a small part in the guide, but I need to test it more thoroughly. In the end, I'd like to have a configuration that AIDE is running on the host, mounting the guest file systems, scanning the necessary files and sending out reports, all one at a time (snapshot, mount, scan+report, unmount, destroy snapshot, next).
If anyone has pointers towards such a setup, it'd be greatly appreciated. It provides, in my opinion, a secure way of scanning systems even if they are completely compromised (in other words you couldn't trust anything running inside the guest or running with the libraries or software within the guest).