How to set javax.xml.transform.TransformerFactory in EAP 6

Issue

In JBoss 5 we used to set the property javax.xml.transform.TransformerFactory via JAVA_OPTS in the startup process.

Doing likewise with JBoss 6 shows the following error:

Exception in thread "main" javax.xml.transform.TransformerFactoryConfigurationError: Provider org.apache.xalan.processor.TransformerFactoryImpl not found
    at javax.xml.transform.TransformerFactory.newInstance(TransformerFactory.java:108)
    at __redirected.__TransformerFactory.<clinit>(__TransformerFactory.java:66)
    at __redirected.__JAXPRedirected.initAll(__JAXPRedirected.java:82)
    at org.jboss.modules.Module$1.run(Module.java:126)
    at org.jboss.modules.Module$1.run(Module.java:113)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.jboss.modules.Module.<clinit>(Module.java:113)
    at org.jboss.modules.Main.main(Main.java:255)

Which seems to be normal because the library isn't loaded at boot time.

What is the way to change the XSLT processor in the last JBoss?