The ´site_deactivation´ app requires thatdjango's flatpages app is also added to your django project.

• copy the ´site_deactivation´ app to your PYTHON_PATH
• add the ´site_deactivation´ app to your INSTALLED_APPS
• add the ´django.contrib.flatpages´ app to your INSTALLED_APPS
• add ´django.contrib.flatpages.middleware.FlatpageFallbackMiddleware´ and ´site_deactivation.SiteDeactivationMiddleware.SiteDeactivationMiddleware´ to your MIDDLEWARE_CLASSES as the topmost entries in that order.
• run ´python manage.py syncdb´

Go to your admin panel and you'll find a new entry ´Site Deactivations / Redirects´ under the ´Sites´ group. In order to temporarily disable an entire site and let it redirect to a static URL, simply create a new entry there, specifying the SITE you want to disable and the redirect URL. This redirect URL could be a reference to a django flatpage.

Beware though that deactivating a site in fact deactivates all pages of that site, except the flatpages linked to the SITE_ID. So the redirect URL you specify either needs to be directing to a flatpage or it needs to be for a different SITE_ID in order to work properly!