Hello gvino,
This is what I did: I downloaded mysql-connector( mysql-connector-java-5.1.18) then copied the jar file to the jbpm-installer\db\driver\mysql-connector-java-5.1.18-bin.jar,
then after installing the ant.install.db there will be mysql folder in C:\jbpm-installer\jboss-as-7.0.2.Final\modules\com\mysql\main then you edit the module.xml
<module xmlns="urn:jboss:module:1.0" name="com.mysql">
<resources>
<resource-root path="mysql-connector-java-5.1.18-bin.jar"/>
<!-- Insert resources here -->
</resources>
<dependencies>
<module name="javax.api"/>
<module name="javax.transaction.api"/>
</dependencies>
</module>
After you run your database and ant start.demo it won't start the H2 coz you have edited all the xml files to mysqlDialect and the drivers. Please update me after doing this what happen.