use CGI::Carp qw( fatalsToBrowser );
use CGI qw( -headers_once );

my $q = new CGI;

BEGIN {
    CGI::Carp::set_message sub {
        my $error = shift;
        $q ||= new CGI {};    # !!!
        print $q->header(),
              $q->start_html( "Error" ),
              $q->h1( "Error" ),
              $q->p( "Sorry, the following error occurred:" ),
              $q->pre( $q->i( $error ) ),
              $q->end_html();
    };
}

##</code><code>##

    ## REALLY UGLY KLUGE FOLLOWS, USE AT YOUR OWN RISK:
    my $fatalsToBrowser = \&CGI::Carp::fatalsToBrowser;
    no warnings 'redefine';
    *CGI::Carp::fatalsToBrowser = sub {
        local $ENV{GATEWAY_INTERFACE} = "CGI-PerlEx-FAKE";
        &$fatalsToBrowser;
    }