I'm currently working on a tool that will be used to add some parts to the checkout page.

I have been looking at the core files but so far I haven't found anything about how to actually pre-set fields to the checkout (shipping details section).

I have no problem adding products, etc.

EDIT: This script is beeing used for a customer to reorder the same products again. By code I can add the products to the cart. This question is regarding the customer details such as firstname, lastname, address, phone, email and have them added to the cart.

closed as unclear what you're asking by MeenakshiSundaram R, 7ochem, Rajeev K Tomy, liyakat, Amit Bera Jun 19 '15 at 4:30

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.