Have user register or login on cart instead of checkout in drupal commerce Is it possible to have the user account pane in the cart instead of the checkout?

I need to have users logged in or registered on the cart, because when users checkout I have a custom rule to change the order to a custom state "awating approval", and sends the user to a custom page with some text. Once the order is approved by the staff the state is changed to another custom state "approved" and a custom rule sends an email to the user so he can checkout and finish paying.

The problem is that if the user hasn't enetered his details before attempting to checkout, the email won't be saved and we have nowhere to send the user an email to finish checking out once the order is appproved.
Is it possible: Yes.
Should you do it: No.

Why?

Having the user account pane at the the cart is a bad idea, since it probably would be very complex to do, and that there isn't really anything that hinders the user to start the checkout flow. You are also forgetting a very important thing.

The Commerce checkout flow is very customizable. This means that you can define extra pages in the checkout flow, and via the interface customize what should be displayed in each page. A much better solution would be to create an initial checkout page with account info only, an extra page that displays info about the order being validated and not allowing to process the order until it is approved. Once approved, the link could simply be that checkout page which with the updated order status can be skipped.

This will keep the customer in the checkout process and leverage the Commerce flexibility.