There are new functionality in Solid Edge ST2 which makes this a whole lot easier! You can dimension a sphere by doing a live section on the part. Not only does it give you a cross section which on which you can place dimensions, you also drive the model with these dimensions. Attached is a screenshot.
If you’re using Solid Edge or another 3D CAD system and are interested in exploring designing with synchronous technology, this is the place to start. These materials will help get you going.