You can. The code would look like:

  my $sub_handle = sub {
    my($expat, $element, %attrs) = @_;
    if($element eq $targetElement){
      print "Target = $targetElement\n";
       if(%attrs){
    while(my($key, $value) = each(%attrs)){
      if($key eq $targetAttribute){push @results,$value;}
    }
      }
    }  
  }

  my $parser = XML::Parser->new(Handlers => {Start => $sub_handle});
  my @results;
  print "$location, $targetElement, $targetAttribute, $file\n";
  $parser->parsefile($file);

  if($location eq 'first'){return $results[0]}
  if($location eq 'last'){return $results[-1]}
  else {return @results}
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(Note the reordering there) sub with no name creates an anonymous sub and returns a reference, so just do that first and use the reference it returns rather than taking a reference to a named sub.