You can go with this tutorial.
It is a little bit older but still works without a problem.
Mysql is replicated per master-master replication. Which works in wheezy a little bit diffrent as in the tutorial.
File replication is done per unison, you can do it as written. maybe some more folders. depends on your setup.
ispconfig is installed as expert mode, because the mysql is a master-master replication, the db has to be named different then the one for server 1.