Alteration To PHP Script To Personalise it and to make alterations user friendly

Hi, I have just purchased the rights to a php script for automating a payment solution with a dvd/cd automatic fulfillment business. I want the script modyfied so I can ulpoad it to my website and log in to a control panel and input details into a control panel to change details instead of me having to alter the actual script. There are a few scripts out there doing this for paypal but I would like to intergrate 1shopping cart instead. Please only people who can actually do this as I have no knowledge of this. ## Deliverables I would also like branding on this product. I will provide a logo and details.