Changing the "Domain" Value inside the Admin Area.

[Nethinks]

I got the following problem: I want to change the value inside the "Domain" Field inside the Admin Area.  Using {debug} inside my smarty template i already found the correct array and key name to change it (at least i think so), but nothing worked so far. The value i want to change it to is stored inside $params['customfields']['Domain'] :

$params['moduleParams']['domain'] = $params['customfields']['Domain'];
$moduleParams['domain'] = $params['customfields']['Domain'];
$params['domain'] = $params['customfields']['Domain'];

Im currently executing this inside the  "Create" Function of my Module.