print $cgi->header(-type=>'text/html', -charset=>'UTF-8');

##</code><code>##

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

##</code><code>##

use Encode qw( decode encode );

print $cgi->header(-type=>'text/html', -charset=>'iso-latin-1');

my $utf8_html_from_src = ...
my $html_from_src      = decode('UTF-8', $utf8_html_from_src);
my $html_to_send       = process($html_from_src);
my $latin_html_to_send = encode('iso-latin-1', $html_to_send);

print($latin_html_to_send);