The only two parameters I believe will vary in the drawing of the ellipses for the meridians are the minor radius (the major radius will always be the same as the radius of the sphere) and the 2D rotation of the ellipse.
For the prime meridian, the rotation is 0 and the minor radius is effectively 0 as well.
For the meridian at longitude 90º, the rotation is 90º (Math.PI / 2) and the minor radius is Math.cos(alpha).