Technically, its easier than a suspension lift, but they can be a real pain in the ass for many cars. The lift itself is fairly simple. You just need to find the mounting bolts, loosen them on one side, jack up that side, install the pucks, and remount the body with longer bolts. Then repeat for the other sides.
Like I said, they can sometimes be a pain in the ass. I'm sure the ML won't be easy to work with here. One inch is a very moderate amount, and I'm not sure if an extension is needed for the shifter. All hoses, lines, and gas filler opening should be fine with a one inch lift. Steering column should also not be affected, but again, I'm not sure.
Also, new brackets to mount the bumpers will need to be fabricated, or you will have a 1" gap between the bumper and the body.
In theory, its simple, but expect just as much work (if not more) as for a suspension lift. This is just a possibility that I'm considering, and I'm not 100% sure I'd like to attempt it. If I do, I'll be glad to do a write up with pics, but for now, I'm just exploring some options for the ML.