{
   package MyParser;
   use base 'HTML::Parser';

   sub start {
      my($self, $tagname, $attr, $attrseq, $origtext) = @_;
      if($tagname eq 'blockquote') {
         $capturing{blockquote}=1;
         $text{blockquote}="";
      }
   }

   sub end {
      my($self, $tagname, $origtext) = @_;
      $capturing{blockquote}=0 if $tagname eq 'blockquote';
      # Do whatever you want to do with $text{blockquote}
   }

   sub text {
       my($self, $origtext, $is_cdata) = @_;
       $text{blockquote}.=$origtext if $capturing{blockquote};
   }
}

my $p = MyParser->new;
$p->parse_file("foo.html");