If you prefer to use jboss connection  pool,
1- define your datasource in jboss, ( you can find sample data source definitions in jboss.org)
2- change your hibernate.cfg to use the defined datasource.

Then you have to decide whether you like to use CMT or BMT transaction management ( in normal scenarios it's better to use CMT - because everything is handled by the container ), so you have to add the following entries to your hibernate.cfg as well ( in CMT ):

<property name="hibernate.transaction.factory_class">org.hibernate.transaction.CMTTransactionFactory</property>
<property name="hibernate.transaction.manager_lookup_class">org.hibernate.transaction.JBossTransactionManagerLookup</property>