No responses but eventually figured it out.
MeshSurfaceSeries meshSeries = (MeshSurfaceSeries)Chart.Series[0];
meshSeries.AutomaticPalette = false;
meshSeries.Palette.Add(0, Color.White);
meshSeries.Palette.Add(0, Color.Blue);
meshSeries.Palette.Add(25, Color.BlueViolet);
meshSeries.Palette.Add(50, Color.Purple);
meshSeries.Palette.Add(75, Color.YellowGreen);
meshSeries.Palette.Add(85, Color.Yellow);
meshSeries.Palette.Add(90, Color.Orange);
meshSeries.Palette.Add(95, Color.OrangeRed);
meshSeries.Palette.Add(100, Color.Red);
Companion snippet: set custom gridlines correlating to the above colors
Chart.Axis(StandardAxis.PrimaryY).NumericScale.MajorTickMode
= Xceed.Chart.Core.MajorTickModeNumeric.IrregularSteps;
Chart.Axis(StandardAxis.PrimaryY).NumericScale.CustomSteps.Clear();
Chart.Axis(StandardAxis.PrimaryY).NumericScale.Max = 100;
Chart.Axis(StandardAxis.PrimaryY).NumericScale.CustomSteps.Add((double)25);// 25%
Chart.Axis(StandardAxis.PrimaryY).NumericScale.CustomSteps.Add((double)25);// 50%
Chart.Axis(StandardAxis.PrimaryY).NumericScale.CustomSteps.Add((double)25);//75
Chart.Axis(StandardAxis.PrimaryY).NumericScale.CustomSteps.Add((double)10);//85
Chart.Axis(StandardAxis.PrimaryY).NumericScale.CustomSteps.Add((double)05);//90
Chart.Axis(StandardAxis.PrimaryY).NumericScale.CustomSteps.Add((double)05);//95
Chart.Axis(StandardAxis.PrimaryY).NumericScale.CustomSteps.Add((double)05);//100
Imported from legacy forums. Posted by Sam (had 1259 views)