While Redruzerkruzer is 100% correct in saying that by banning something like the book binder would prevent ages from being created, you can go even further.
Our server controls Mystcraft ages in a way that only those who have been granted access to ages can, well, access them! This even takes into account a player's ability to teleport/send teleport requests.
Using a permission plugin like GM or PEX, along with a world permission node plugin like Essentials, you can disable teleportation/specific commands for the Mystcraft ages.
This could allow Admins to force teleport players to their ages if they want, but then prevent that player from being able to use /back or /sethome in those ages.
If you are trying to set this up for a premium/donor feature, then you must take into account world/player specific permissions. You might not like it when a layer decides to create an infinite lava age and then hands out access to it to everyone on the server, resulting in infinite power. In fact, we don't even allow premium players to make such ages, but do allow them to invite friends into their ages.
