facebook third party cookies

I have three pages built into an iframe app (non-fan landing page, fan landing page - which has a form on it, and a subsequent page for when the form is submitted. However, I need to only show the fan page with the form once, so a third party cookie I believe is required?? If necessary we can link the form to a database to check IP address/email address submitted etc. Grateful for an experts view on the best way to achieve this.