Rafael
I did use Gatekeeper on ACS4.5 without problems. It is a very simple proxy system enhanced by the OACS4 security model. As I remember it was very easy to configure and very easy to use, you have to define an internal URL which is mounted in your hierachy and secured by the usual model. Gatekeeper do not use directly any database, it use the general OACS model of mounting instances of packages.
