He has to have internet to re-download the maps onto his 360. He needs to do what's called a license transfer so that the will be removed from your 360 and put onto his. map packs are linked to the gamertag and the console. You can't both use them on 2 360s and you won't be able to use them on your 360 without his gamertag if that's what you guys are trying to do. He needs to bring his whole 360 over to your house, re-download the maps, and follow these steps http://www.xbox.com/en-US/support/systemuse/xbox360/licensemigration/ to transfer the license to his 360.