Try modifying the persistence.xml file which is stored in the db folder and add modify the properties so that it matches the Oracle database.
<property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<property name="hibernate.connection.password">mypassword</property>
<property name="hibernate.connection.url">jdbc:Oracle:thin:@192.168.1.1:1521/mydb</property>
<property name="hibernate.connection.username">my_user</property>
<property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>
Then, you will need to drop the Oracle ojdbc6.jar jdbc driver into the db/driver folder. I believe that will do it.
brian