There is not a specific feature for this.
If you have a V endmill with the correct taper angle that of course would work. It would be a nice application of the ball-nosed w/ taper tooling folks mention (assuming there is one with such a feature)
If you want to do this using a ball-nose tool then it can be done after a fashion, albeit tediously:
Or, one could model it in 3D and cut using Carbide Create Pro