I think you are running at the wrong direction.

Why are you wanting to cache those data? Are your having performance problems?

The only way I know you can do what you want is create a exclusive connection (By the way: Classic Server) to the FB server and ONLY execute select statements in those tables – Customer, CustomerAddress, etc. In that way database cache pages for that connection will stay only on those tables.

Another approach is using for example Delphi´s DataSnap technology. You will cache that data in your DS server and synchronize with Firebird database.

Let me know more about your problem.