#!/usr/bin/perl

use strict;
use warnings;
use CPAN;

my %needed = (
  Some::Module => 1.23, # must have at least version 1.23
  Other::Module => 0, # any old version will do
  ...
);
my @need_to_install = ();
foreach my $module (keys %needed) {
  eval "use $module;";
  if($@ || eval "${module}::VERSION < $needed{$module}") {
    push @need_to_install, $module;
    next;
  }
}
CPAN::Shell->install(@need_to_install);