Liferay: Hook [ENG]

So someone in your management (or in your customer's management) heard that Liferay is cool and decided that you are the one who is going to make it work. You install it, toy with it a little, build your community, translate it in your language, start fiddling with the themes, user permissions and such.
Then one day you have to write your first hook. A hook is a class which handles events or changes in the underlying model structure. For example you might want to do something when a new user is added to the database.
You google around a bit and find a lovely tutorial. Lovely but, alas, outdated, because, you know, to stir things up a bit someone thought to change hooks configuration between version 5.1 and 5.2.
Basically you have to move the hook declaration in a property file. Just a heads up, since I struggled with this a bit.