The Pokémon holding Exp. Share will get the normal amount of EVs from the enemy Pokémon. This means that if the fighting Pokémon is holding a Macho Brace or Power Item to boost EVs, the Exp. Sharing Pokémon won't get the additional EVs, and only get the normal amount. If the Exp. Sharing Pokémon has Pokérus, however, it still doubles the EVs it gets.
Edit: Oh, yea, it would be better if you just have the EV-training Pokémon hold a Macho Brace/Power Item, get sent out first, then switch out right afterwards to a Pokémon that can handle itself.