You could start this out by adding a set cookie server behavior to the details page. When the user gets here you should check to see if this cookie is set, if it is set and less than 2 then you would add one to it, if it is not set then you would create it and set it to 1.
You could then add in another check to see if the cookie value is 2 or greater, if it is then the user should be redirected to a registration page or whatever page you would like them to go to.
Next you would want to make sure you have your user login and registration pages setup, you can use Security Assist to do this.
The last part would be to add an access rule to the detail page, inside of the rule you would want to move all of your cookies code so that it will not be used if the user passed the login rule.
This is just an overview the specifics will require some custom coding to get properly implemented. For the cookies stuff you would use cookies toolkit. Please post back with questions that you have about any part of this and we would be glad to give some advice and pointers. Since it is a custom implementation we will be limited in the amount of support we can provide for the custom stuff but we will be glad to advice and check some things out for you.