One of the restrictions of Vcarve is that while it is great for 2D/2.5D CAM. it can't do this 3D kind of thing. Unfortunately, it's not straightforward in gcode either. If you use the G2/G3 arc/circle commands, you can either cut a circle at a single depth, or cut a circle with steadily increasing depth by advancing in Z while cutting the circle with constant radius. No tapers.

I would suggest that you could look at Fusion 360 which has a full CAM capability which would produce this kind of gcode. There is a bit of a learning curve involved (depending on where you are coming from - this could be an understatement!) but it could do what you want and it's free for home and hobby and small commercial users.