I like your code, but I am on solaris, not win32. I used your while loop, but I kept getting asterisks even after I pressed return. In other words, the while loop never ended. Here's what I am using:

print " Enter your password:\n";
ReadMode 3;
while($key = ReadKey()){

    $val = ord $key;
    push @password, $key unless $val == 8 || $val == 13;
    last if $val == 13;
    print "*" unless $val == 8;
}
[download]

By the way, what does the 8 and 13 correspond to? I am sure that may have something to do with the problem.