If you do not insist on using XML::Twig then with the use of a global variable:

use strict;
use XML::Rules;

my %data;
my $parser = XML::Rules->new(
    stripspaces => 7,
    rules => {
        _default => '',
        url => 'content',
        urlInfo => sub {
            my ($tag,$attr,$context,$parents) = @_;
            $data{ $attr->{url} } = $parents->[-2]{name}
        },
    }
);

$parser->parse(\*DATA);
use Data::Dumper;
print Dumper(\%data);

__DATA__
<authenticationReports>
<generatedTime>Tue Sep 29 07:07:34 PDT 2009</generatedTime>
...
[download]

use strict;
use XML::Rules;

my $parser = XML::Rules->new(
    stripspaces => 7,
    rules => {
        _default => 'content',
        urlInfo => sub {
            return '@url' => $_[1]->{url};
        },
        application => sub {
            return 'url' => $_[1]->{url};
        },
        appDeploymentFile => sub {
            return '%urls' => {
                map {$_ => $_[1]->{name}} @{$_[1]->{url}}
            }
        },
        authenticationReports => sub {
            return $_[1]->{urls}
        }
    }
);

my $data = $parser->parse(\*DATA);
use Data::Dumper;
print Dumper($data);

__DATA__
<authenticationReports>
<generatedTime>Tue Sep 29 07:07:34 PDT 2009</generatedTime>
...
[download]