I asked around about this to some to Adobe experts and this is the reply i got:
"This can be definitely be done. They would need to write a function to identify when the ad comes in to view. At this point they can fire a separate event and capture the campaign value in a different evar. Note, if the same evar is used to check for view-through and click-through campaigns, they need to make sure they understand how the attribution is being done."