Make MVC3 website authenticate both Windows and Forms

Question

I am developing an MVC3 application for a customer service team. I am using default login and registration controls in my application. I have to use both Form Authentication and Windows Authentication. For the customers who come online to insert their comments, it will be Form Authentication for them. For the customer service staff, the system has to use their Windows Authentication to login them (if they they have logged into the their windows account the website should recognize their login details and authenticate them.) How can I make my MVC3 application to authenticate both Windows Authentication for the staff and Forms Authentication for others? Thanks