use WWW::Mechanize;
my $mech = WWW::Mechanize->new();

$mech->get( $url1 );

$mech->add_header( 'Cookie' => $cookie1 );
$mech->get( $url1 );

$mech->delete_header( 'Cookie' );
$mech->add_header( 'Cookie' => $session );
$mech->default_headers->authorization_basic($browser_username,$browser_password);
$mech->get( $url3 );

...