Just download the latest jdbc4 driver and place it into JBOSS_HOME/modules/org/postgresql/main. Then create a file module.xml in the same folder with the following content (replace filename if necessary):
<?xml version="1.0" encoding="UTF-8"?> <module xmlns="urn:jboss:module:1.0" name="org.postgresql"> <resources> <resource-root path="postgresql-9.1-901.jdbc4.jar"/> </resources> <dependencies> <module name="javax.api"/> <module name="javax.transaction.api"/> </dependencies> </module>