I don't quite understand. I have updated the code (to the best of my ability) to use the CGI module. Perhaps, I am leaving something out. Keep in mind that the actual script will accept any number of parameters through an HTML form.

#!C:\Perl\bin\perl.exe

use strict;
use warnings;
use CGI;

my $req_meth = CGI->request_method();

sub readPostInput() {
    my (%searchField, $buffer, $pair, @pairs);
    if ($req_meth eq 'POST')
    {
        read (STDIN,$buffer,$ENV{'CONTENT_LENGTH'});
        @pairs = split(/&/, $buffer);
        foreach $pair (@pairs)
        {
            my ($name, $value) = split(/=/, $pair);
            $value =~ tr/+/ /;
            $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/e
+g;
            $name =~ tr/+/ /;
            $name =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg
+;
            $searchField{ $name } = $value;
        }
    }
}

my %postInputs = readPostInput();

print "Content-type: text/html\n\n";
print "Complete :: $req_meth";
[download]

After these changes I still receive the same error.

use strict;
use warnings;
use CGI;

my $req_meth = CGI->request_method();
my %postInputs = CGI->Vars;
...
[download]

Still you haven't answered the most important question: Is the script run as a CGI script? That is, is there a web server that executes it with the CGI protocol?

Perl 6 - links to (nearly) everything that is Perl 6.

This script, I believe, is not run as a CGI script. I say this because I haven't yet used the CGI module in it. HTML is ouput using templates, and any data is stored into DAT files simply by opening them and writing to them.

I hope that answers your question.