/ Published in: PHP
I’ve implemented something similar a couple of months ago. What we wanted was to prevent the cart from the old session from merging into the cart of the current session at the point when the customer login. If that describes what you want as well, then the way I did it was to overwrite Mage_Checkout_Model_Observer. The function loadCustomerQuote() in the observer observes the event customer_login and merges the current session quote with the last login quote object
URL: http://www.magentocommerce.com/boards/viewthread/73612/