EDIT: Your wording is a little confusing, but if I understand correctly, then yes Miltank will gain attack EVs, but it will only gain 1 EV since the experience share only transfers EVs that your pokemon would have got if it were the one actually battling....If that makes any sense. So it doesn't gain 4 attack EVs, only 1. =(
Future questions like this can go in the
Request a Moveset / Simple Q&A thread in Strategies and Movesets.
*closed*