How long does it take a developer to install PayPal Website Pro?

If you're not an actual developer, please don't submit dumb a$$ answers to this question. How long should it take the developer to install PayPal Website Pro with customization of API into a website? I intend to make this payment option available for Customers (domestic & international) who will be using PayPal to check out and complete purchases on my website. The customization will entail PayPal showing the order details of the Customer's total order based on Order Total & Zip Code all dependent upon which Courier Delivery Service the customer has shown to deliver their package to them. If you've completed a similar installation, how long did it take you to install PayPal Website Pro for your client? Thanks in advance answering my question.