Basically I have a few landing pages with forms with fields that are a subset of the checkout page form fields. I'd like for the user to submit the form and be redirected to the checkout page with the form values already filled.
I'm using Übercart and I think it's this function here that controls it:
function uc_checkout_pane_delivery($op, &$arg1, $arg2) and the values of $arg1 needs the be set by the previous form. My question is how? What would be an appropriate method for populating the checkout form fields? Thanks.