WorldEdit - Spawning in Elliptical Structure

I know you can do //sphere to spawn in a perfect sphere, but is there a way to make it more elliptical?

What I mean is that //sphere creates a perfect sphere, of say, a radius of 5 blocks

But what if I wanted this shape to be 10 block radius horizontally but 5 high?

 

This creates a cylinder. What I want is something like this: http://i.imgur.com/YcMAoia.jpg (that was created via MCEdit)

 

I cannot get it to work, it is only making cylinders for me

 

THANK YOU