Well, I would guess from the lack of answers that you can't. How do you guys allow the user to configure the enterprise beans? I see a couple of options, none too atractive:
1. Change ejb-jar.xml and redeploy the bean. This is a little bit to much for a production server.
2. Implement your custom configuration using JDBC and create a GUI for it.
3. Load the properties from the file system. This is not really recommended in a distributed EJB environment.
4. Use JMX. This is not persistent.
As an example, in the standalone tomcat you can place a context definition file under the conf directory with environment entries for the web application.