Are you asking for advice on how to model this or on how to create a detail? We cut spheres on a daily basis. For the detail drawings we specify each hole y degrees down from north pole, and x degrees along the equator from a datum plane. The origin of the part is usually the center of the sphere. Most holes are cut towards the origin but now and then a hole may be offset. These are specified same as described above only with an additional x,y offset.