When I read that article I was a bit confused as to how that angle could be cut. I had to read it a few times and actually picture myself doing the steps to figure it out. Now I haven't actually cut this myself yet, but I believe that if you follow the directions exactly as they are written it should work itself out for you. Just set your saw at a 30° angle like it says, set up a 'fence', and using a spiral blade you should be ready to cut. Just make sure you don't use a straight blade if you don't have to because it will tend to drift a bit and you won't get a straight cut angle (does that even make sense?

). When you do the second side you will have to use that push stick also to be sure you get an even angle on the other side. I know it's confusing, and sometimes mistakes are made in magazine articles, but this time it should be right and work out fine.
Good luck, and remember to post a picture here when you are finished.