Log4j: Changing XML with DOMConfigurator?

I am using log4j with Java and wanted to configure my XML-Config-File (I need to use XML for the ErrorHandler), so that some Properties in the XML (like the Backup-Value for th开发者_StackOverflow社区e RollingFileAppender) could be changed within the DOMConfigurator of the log4j-API. This class also got the subst()-method, which should substitute the chosen values, but I really don´t know how to handle it.

If their is no way changing the config with the DOMConfigurator, which else possibilities did I got to easily correct values in an ambiguous XML-File (So to say, because the XML-Tags are not unique or only their Tag-names, which are values itself)? My XML is kind of static or hand-written.

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Why can't you fix the original XML file on the disk?

If for some reason that's not possible, I would rather try altering the configuration directly via Logger, after the config file has been loaded.