I know I can change the customer group with this code:
$session = Mage::getSingleton(\'customer/session\');
$customer = $session->getCustomer();
$customer->setGroupId(\'2\'); // custom group id
But that doesn\’t work if the customer isn\’t logged in. How to change te customergroupid for not logged in customers?
I want to assign them after filling in a zip code on the homepage to display the products that belong to their zip code / customer group!