Login/Register with S2Member in WP-eCommerce

I am using WP-eCommerce with the option “Users must register before checking out:” set to “Yes” in the “Checkout” tab. The result is very messy and user unfriendly – as it ask the user to complete all the billing information and “Purchase” before it actually register the user – just to ask for the billing information again. Also – it does not use the elegant S2Member user registration process i.e. sending the user the registration details, etc. Am I doing something wrong?

What I would like to see at the time of Checkout when the user is NOT Registered/logged on: User Registration via the S2Member Registration form – which send the registration details & password to the user. http://mysite.com/wp-login.php?action=register

How do I managed to do that?