I don't see how being in a text file rather than an xml file, which is also a text file, is any easier to change. Arguably having more than one place your SessionFactory is configured may make the applciation less easy to configure? But that is not to say you can't do it. There are a number of ways of doing this:
Have a look at the Configuration class. It has a number of ways of specifying where the configuration file is and what its called.
You can also configure the SessionFactory using a properties file (by default hibernate.properties will be used if it is on the classpath). One weakness this has over an XML file is you no longer have the extra validation XML can provide against a schema or DTD
You can supply extra properties as system properties, so this could be a parameter entered when running your application
You can do all this programatically, so can use any other mechanism you can dream up if you are willing to take the time to code it