Usually if you preorder something with some sort of bonus on Steam you'll get the activation codes with the game under the CD Key heading on the game's library page, but this could be an Amazon exclusive or something. If it didn't explicitly say you'll get it as a preorder bonus then you won't get it, I've never had to email Valve about missing codes because they - assuming there are enough codes to go around, they do occasionally sell out - always provide codes when required.
This has been a weirdly written post, it must be said.