How do I add a customer ID field in Ubercart? I want to ask for the customer to enter his ID when he buys something.
Is it hard to add a new field apart from the default: name, phone, address, etc?
You want to add a field to the checkout process? There are two modules that do that. uc_webform_pane allows you to create webform nodes that integrate into the checkout process. uc_cck_pane allows you to integrate cck nodes into the checkout process.