I was nervous about putting mine on to, but it didn't turn out to be too hard.
Start at one end ( I started at the back) hook it over the lip and twist down, then just start banging it on with your hand with a downward motion (sort of bang it on and drag the palm of your hand downwards at the same time) should go on pretty easy.
I did have a bit of trouble at the front on the A pillars where there is about 3 layers of sheet metal and aluminium trim to hook over, but got them on eventually, I also found the trims to be just a tad to long, so had to cut a fraction off (about 3mm from memory) and file up the end, this can only be done at the front as the rear has the end closed up.
Good luck!