Supposedly 1 1/2 hours of work; my wife and I spent more like 2 1/2 hours. Admittedly, we were being very, very careful, and my 5/16" drill bit is sufficiently unsharp that I had to start with a 1/8", then 1/4" drill bit to get pilot holes going into the aluminum blade. I am a bit unclear on why they did not do this at the factory; it did not really make the box much smaller, just a different shape.
It is a very clever design. In the down position, the blade rides up and down on a metal frame so that changes in grade cause the entire blade assembly to go up as needed; gravity brings it back down again. The angle of the rubber part of the blade means that going forward it digs in; going backward causes it lift up on the frame.
The theory seems to be that you put the frame into the 2" trailer hitch receiver at the start of the season, and leave it there. You lift the snowplow blade onto the frame. In the up position, it hooks in place so that you can drive around, and it does not block the headlights (at least on the TrailBlazer). To put it in the down position, you unhook two pins, lift the plow up over the up position slots, and drop it down to the ground. Then you reinsert the retention pins so that it can't fly up and off the frame.
Inserting the frame is a bit annoying because of weight and because it will be cold and snowy when you need this gadget, so I expect to put the frame into the hitch receiver at the start of the snow season and leave it there. Taking the blade off the frame or putting it back in place is a task that I can do myself, but my wife will probably have trouble doing alone, except at the risk of causing the other shoulder to demand surgery a bit sooner. I will certainly be much more buff in the upper body if I have to do this regularly.
The one area that I am a little disappointed in concerning direction. I thought that it was adjustable to point either straight ahead, or to the left or right. But that appears to be the considerably more expensive HD model (that's Heavy Duty, not High Definition). I think I see a way that the frame on which the blade rides could be modified (or replaced) so that it gives that same capability. A friend of mine has just started a welding business; perhaps I will throw the idea at him.