In Hitman 2, on professional (regular) difficulty, the guards and other NPCs are more aware of their surroundings and less triggered by distractions in other rooms.
I was able to get the achievement mostly following the Maka video from hitman 1 but improvising a little bit.
Instead of waiting for Jasper and the guard to leave the room from the ledge like in the video, enter the building from the bathroom (3rd window from the left). When you enter the bathroom from the window, wait until Jasper and his guard go to leave the room for the first time. Jasper will leave the room first and his guard will hesitate before starting after him. This will create a small window of time when Jasper’s back is turned/out the door of the office. Subdue the guard, dump his body in the bathroom storage container and wait for Jasper to come back. As soon as he stands in front of the table, silently kill him any way you choose (use fiber wire, silenced pistol, snap neck, etc.). Don’t wait too long or the Colonel will join the room, complicating matters further…
Once you kill Jasper, dump his body in the same storage container in the bathroom that holds the guard and make your exit.
OK here is where things also change in strategy. Instead of following the Hitman 1 video and going out of the bathroom window, use the window closest to the maps on the wall. This will keep the guard below you from spotting you as you’re making your way to the pipe on the ledge. Once you hit the pipe, slide down and crouch run the way you entered, using the bushes for cover as needed. Upon mission completion, your achievement should pop.