package Config_m;
use Config;

my $tied = tied %Config;
$tied->{mydomain} = 'new value';

1;

##</code><code>##

use Config_m;
use Config;

print $Config{mydomain};
# outputs 'new value'

##</code><code>##

use Config;
$obj = tied %Config;
$obj->{mydomain} = 'new value';

print $Config{mydomain}, "\n";

#outputs 'new value'