Work with a Buddy to subvert a mission offered by a faction

The first chance you get to get this mission is Main Mission 4 as long as you don't kill all your buddies before hand. This is the mission where you have to Assassinate a local chief constable for the APR. You can ether intercept his car and kill him or if you want the achievement your buddy will phone you offering you a better way of killing him, do your buddies way to get the points.