When I worked at game stores(post TG-16), when we got a promo from the company, it usually was some POP to put on the display box(read: sticker) and then we just grabbed the promo item from the stock case at the time of sale. I do not recall being asked to open up the console box(breaking any seal) just to drop in the game. Of course if the promotion was handled in-house, we'd get systems pre-loaded with items and pre-stickered.
I'm pretty sure my TG CD-ROM that had the CD+G sampler disc promo, the disc was handed to me or the salesman dropped it in the box at point of sale.