I would like to add the Log4Perl configuration into the very same xml files, but I have not really understood how I could do this.
Make it just another key/value pair

my $log4perlconf = 'blah blah blah blah blah';
$conf->{log4perlconf} = $log4perlconf;
...
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I realize that there is a Log::Log4perl::Config::DOMConfigurator module, but I am not sure how this is linked to Log4Perl.
What do you mean by "linked to Log4Perl?" Its just an extension, an add-on... Instead of writing your config in Log::Log4perl::Config format, you write it in xml (log4perl.dtd or log4j.dtd)

Is this module ignoring all parts which are outside the xml configuration?
???? Not sure what you're asking, but I think the answer is no.