The handler is always called with just 2 parameters, the twig and the element. So if you want to add new elements, you have to use a closure: make the handler an anonymous subroutine. It can then use lexicals in scope when it is defined. It might sound complicated, but practically it is very simpleand natural:

my $t= XML::Twig->new( twig_handlers => 
                           { 'JOB_SECTIONS/SWITCH' => sub { $self->_up
+load_job( @_) } },...
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You can get much better explanations about what's going on there in Simon Cozens Achieving Closure.