Rather than messing with Win32::API (which I've never gotten to work for 64-bit), you can use Win32::Console::OutputCP(). This produces the required output:

use Win32::Console;

binmode(STDOUT, ":unix:utf8");

Win32::Console::OutputCP( 65001 );

$line1 = "\x{2554}".("\x{2550}"x15)."\x{2557}\n";
$line2 = "\x{2551}".(" "x15)."\x{2551}\n";
$line3 = "\x{255A}".("\x{2550}"x15)."\x{255D}";
$unicode_string = $line1.$line2.$line3;

print "THIS IS THE CORRECT EXAMPLE OUTPUT IN PURE PERL: \n";
print $unicode_string;
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