Registration redirect

[Simplicity]

I use a seperate registration system which unites my CMS, shopping cart and forum together, this uses the forum database to store user data but uses a seperate registration form, bypassing the forum registration process.

This is all fine, except I miss the ability to have the user agree to the site and forum rules before registration.

How could I go about having the user go to register.php view the rules and upon clicking the agree button they get redirected to another script?

Any help on this would be greatly appreciated