<?xml version="1.0" encoding="UTF-8"?>
<module xmlns="urn:jboss:module:1.1" name="org.postgresql">
     <resources>
         <resource-root path="postgresql-9.1-902.jdbc4.jar"/>
     </resources>
     <dependencies>
         <module name="javax.api"/>
         <module name="javax.transaction.api"/>
         <module name="javax.servlet.api" optional="true"/>
     </dependencies>
 </module>

/subsystem=datasources/jdbc-driver=postgresql-driver:add(driver-name=postgresql-driver, driver-class-name=org.postgresql.Driver, driver-module-name=org.postgresql)

<?xml version="1.0" encoding="UTF-8"?>
<datasources>
  <datasource jndi-name="java:/datasources/some-ds" enabled="true" use-java-context="true"
        pool-name="some-ds-pool">
    <connection-url>jdbc:postgresql:dbname</connection-url>
    <driver>postgresql-driver</driver>
    <security>
      <user-name>username</user-name>
      <password>password</password>
    </security>
  </datasource>
</datasources>