Is this the sort of thing you're after?

use Term::ReadKey;

print "Press SPACE to exit\n";

ReadMode 4;

while ( 1 ) {
    my $c = ReadKey(-1);
    next unless $c;
    last if $c eq ' ';
    printf "%02x ", ord $c;
}

END {
    ReadMode 1;
}
[download]

I think Term::ReadKey works on windows.