Discount label for product combination

How do I make a promotion such that the affected product combination shows the discount label and discount price in the storefront?

  1. catalog promotions show discount labels, but apparently they can't be defined for specific product combinations (?)
  2. cart promotions work, but they will not show to the customer in any way, which I, from a marketing standpoint, fail to understand completely
  3. using the list price you can get the discount label to show, but again, you can't define the list price for a certain combination

    Thanks for any help,