I think you can manipulate which expansions are available by using the data found here:
http://www.eqemulator.net/wiki/wikka...les#Expansions
You could also achieve this by locking out zones in the zone table. Setting the min_level = X where X is greater than the max level attainable on the server. Or you could set min_status = 250 so that only GM's and admins could access the zone. Or you could create a custom item that isn't available in the game world and make it the required key for the zones you want locked.