opt in form for shopping cart - other work too

We have javascript that needs to insert username and a custom field, ad source, into 1shoppingcart on a certain landing page. Right now, 1shoppingcart gives us code to use but it isn't working -- it's inserting the email address but not a custom field. We have a lot of this sort of work. Hourly is probably best so we can give you more tasks under this Freelancer assignment. You must be FAST. And good communication is a MUST. Meeting deadlines, essential. I would like to see at least 5 completed assignments on Freelancer with high feedback score. Be sure to post at least 3 things you've done that are similar such as projects with other shopping carts or 1shoppingcart. Thanks