Hi... didn't see this message before I replied to the other one
Bottom line is that with no internet access, you won't be able to use the software manager, receive the Avert threat alerts, or update the master repository by a pull task. This is far from the end of the world, though: it just makes things a bit more fiddly.
You'll have to manually download point products and extensions from your download site, and manually check them in to ePO. For the DATs you'll have to manually download the ePO-compatible DAT package from the DAT site each day and check that in to the master repository. The Avert threat alerts function is dead, though - there's no manual equivalent - but you can subscribe to our SNS notifications to receive the same sort of information via email.
There's plenty of airgapped ePO installations around - aside from the small annoyance of the extra manual steps, they work just fine