i'm not really sure how to achieve this.

you can try turning off BreakAllSlices and implementing the breaking yourself like this:

        private void ultraChart1_ChartDrawItem(object sender, Infragistics.UltraChart.Shared.Events.ChartDrawItemEventArgs e)
        {
            Wedge w = e.Primitive as Wedge;
            if (w != null)
            {
                w.Center = Infragistics.UltraChart.Core.Util.Geometry.AngularToCartesian(w.Center, 25, Infragistics.UltraChart.Core.Util.Geometry.DegreeToRadian(w.startAngle) + Infragistics.UltraChart.Core.Util.Geometry.DegreeToRadian(w.angleSweep / 2f));
            }
        }

but since the center points in both images are not the same for each wedge, i'm not sure how to get them to line up in a scenario where one slice is > 180 degrees.

an alternate way to achieve this is by inserting a white "separator" wedge in between existing wedges.  again, this is with BreakAllSlices turned off:

private void ultraChart1_FillSceneGraph(object sender, Infragistics.UltraChart.Shared.Events.FillSceneGraphEventArgs e)
        {
            PrimitiveCollection primitivesToAdd = new PrimitiveCollection();
            for (int i = 0; i < e.SceneGraph.Count; i++)
            {
                Wedge currentWedge = e.SceneGraph[i] as Wedge;
                if (currentWedge != null)
                {
                    for (int j = i + 1; j < e.SceneGraph.Count; j++)
                    {
                        Wedge nextWedge = e.SceneGraph[j] as Wedge;
                        if (nextWedge != null)
                        {
                            Wedge separatorWedge = new Wedge(currentWedge.Center, currentWedge.Radius, currentWedge.startAngle + currentWedge.angleSweep - 2f, 4f);
                            separatorWedge.RadiusInner = currentWedge.RadiusInner;
                            separatorWedge.PE = new PaintElement(Color.White);
                            //separatorWedge.PE.Stroke = Color.White;
                            primitivesToAdd.Add(separatorWedge);
                        }
                    }
                }
            }
            e.SceneGraph.AddRange(primitivesToAdd.ToArray());
        }