This is just a thought to maybe help get you going. I havent visted the original solution the book uses in some time.
My inital thoughts are you could use to calendar controls, one for start and end date. There are built in date/time functions that can get the total number of days, or you can get this later using a SQL SP. The only thing that may give you trouble is getting the specific days that reside between your range. However this can be overcome by simply reporting the range and giving the total number of days off.
Hope this helps to get you going.