We configure the UPS/FedEx... etc credentials and other
api details in
Magento Admin Panel.
In cart/checkout page, Magento shows the shipping rates based on configured account details.
If I want to change/show the third party account rates, I will show the custom fields in cart/checkout page based on these credentials, as well as the shipping rates.
If a customer enters values for those custom fields, how can I pass those credentials and get the associated shipping rates.
I mean, which method I should rewrite? Or should I write a new method?
Thanks in advance.