use CPAN;
use strict;
use warnings;
$CPAN::Config = {
  'build_cache' => q[10],
  'build_dir' => q[/full/path/to/your/build/dir],
# etc
  'makepl_arg' => q[PREFIX=/full/path/to/wherever
                    LIB=/full/path/to/lib/perl5
                    # etc
                   ],
# etc
  'wget' => q[],
};
$CPAN::Config_loaded = 1;
my $mod = 'GD';
my $obj = CPAN::Shell->expand('Module',$mod);
$obj->install;