set default start page controling script

Hello, I want you to make a "set as default start page" script that I can use for promoting purposes. People will click on a banner to win a price. After clicking the "set as default start page" must be activated. They will get the standard pop-up "do you agree to set site X as your default start page?" If they click yes, the script will forward them to the page where they can join the competition. If they click no, then they will get the message that only if they set the page as default start page they can join the competition. If you need more details just let me know. If you can bid under the price range, let me know in PM. If you don't have enough funds in this price range, also let me know. Thanks, Kevin