Howto: Set a custom field

I have no idea how this works for two custom fields, but here's how you set for an entity field:

[PHP]
        $customFieldList = new nsComplexObject('CustomFieldList');
        $StringCustomFieldRef = new nsComplexObject('StringCustomFieldRef');
$StringCustomFieldRef->setFields(array(
   'internalId' => 'custentity_mb',
   'value' => 'HELLO THERE'
  ));

$customFieldList->setFields(array(
  'customField' => $StringCustomFieldRef
));

// create array of customer fields
$customerFields = array (
  'isPerson'   => true,
  'firstName'   => $firstName,
  'lastName'   => $lastName,
  'companyName'  => $companyName,
  'phone'    => $phone,
  'email'    => $email,
 
               'customFieldList'   => $customFieldList

//there's more code here (see sample_add_customer.php), but omitting..
);

// create Customer record
$customer = new nsComplexObject('Customer');
// set fields
$customer->setFields($customerFields);