Hello Johann,

If you set None for your label position, you aren't going to get any labels, so I am pretty sure what you are asking for there isn't going to work.

As for the other part, we aren't sure what you are trying to do.  If you are trying to customize the label created, you can use the 

following override off the PieChartDelegate to create a custom label.(in Xamarin)

        public override string PieChartViewLabelItem (IGPieChartView pieChartView, string label, IGPieSliceInfo item)
        {
            // NOTE: Don't call the base implementation on a Model class
            // see http://docs.xamarin.com/guides/ios/application_fundamentals/delegates,_protocols,_and_events
            throw new NotImplementedException ();
        }

in objective C the delegate method would be named

-(NSString*)pieChartView:(IGPieChartView*)pieChartView label:(NSString*)label item:(IGPieSliceInfo*)item;

There isn't a separate value marker in PieChart