Paypal buttons with UPS

Can I setup my paypal buttons so that they show a UPS shipping estimator to the customer, and then charge the customer that estimated amount for shipping, in addition to the product price????

I really need this approach, but from what I can decipher from the paypal tutorials is that the UPS shipping estimator is only used to help the vendor/provider/retailer print out UPS shipping labels AFTER the customer has already purchased the product.

Please advise. Thanks in advance.