Pokemon EVs Question?

I have a Gastly that I want to EV train. It has the Pokerus, so it should get double the EVs than normal. I know that the only two pokemon in Celestial Tower gives off +1 EV in Special Attack. With the Pokerus, it is +2. If I have Gastly hold the Power Lens, how many EVs would it get? Does the game count the item's boost first, then Pokerus, or vice-versa?