Your crown molding is going to have to be special cut. You could do it yourself, however there is a certain pattern that crown mold is cut in to give it its shape (As I am sure you know). One thing to think about in trying to cut it yourself, is that you are going to need a table saw to make your top and bottom cuts. The top and bottom edges are angles either at a 45 degree on both sides, or the more standared 38 degree and 52 degree angles. Without a table saw, you are not going to be able to cut this right, so it will not sit against your wall properly. Also, if you happen to slip you are going to have a noticable spot in your crown molding (and solid wood molding is not cheap).
There are lumber stores that will cut it for you, or you can find one that has this type of crown molding availible for you to order. Just Googole it I am sure it will not be hard to find one that will do it for you, or have the material you need. The machines that are used to cut crown molding get it done with one pass though. the machine also acts as a planer in case there are some thicker spots that need to be evened out. If you need any advise on how to mount your molding look at my answer linked here on How to install crown molding .