Hi,
Instead of trying to populate an existing custom field type with data, I would recommend to create a new type of custom field that you would call for example "serial number" which would display a dropdown of the serial numbers of the current user. Then you could just create a new custom field of that type for the table item (in order to have it on the product page, when the user add the product to the cart) and the selected value would be carried on to the checkout, the order, the email notifications and the invoice.
To create such new types of custom field, you can develop a small plugin implementing our Fields API triggers:
www.hikashop.com/support/support/documen...entation.html#fields
You can find an example of such plugin with the latest version of HikaShop, in the folder plugins/hikashop/datepickerfield which adds the "plugin datepicker" type of custom fields in order to be able to create custom fields for date selection with advanced restrictions.
PS: I already replied to your contact request on the same question via email. You didn't receive it ?