It depends if you need the password in plaintext to pass to something else. If not, you could do a one time shot with the following:

perl -le 'print crypt("your password here", "FO")'
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Then in your actual script

my $password = getpassword();
if ( crypt($password, "FO") ne "crypted password from one-liner") {
   #your code here
}
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However, this provides a false sense of security. There's nothing that prevents someone from copying your script and changing the conditional to if(1) {. One other caveat: don't bother picking a password that's longer than 8 characters; crypt truncates at 8 characters for historical reasons.