Keeping the cart information when login and logging out

[eluser]earlyriser[/eluser]
Hi.
I wonder if some of you have solved this problem. I'm using SimpleLoginSecure and the Cart class
In a ecommerce site the user (unlogged) add some products to his car and then he login. At this moment the cart info is lost because the session has changed.
Do yo have an idea to overcome this?
I would like to keep the cart info independent of the login process.