Well how I did it was I stood where the pic shows (the one of me from above holding the r/l) and I shot grenades at the floor at about a 45 degree angle away from me. They have to hit the lift. While I did this I kept moving back and forward across the centre of the lift - you should keep hearing the hissing noise as it activates. Once in a while it will give up and drop and this is when you dodge off it at the bottom. Probably not worthwhile but ffs someone has to keep this section going