I'm don't know what x-rotation left means, since rotation about the x-axis would normally tilt in or out of the screen.
But otherwise it is simple enough. Add a keypressed event handler to your class derived from ChartView, trap the key you want to trigger on, and call the coordinate systems (pTransform1, made global to the entire class in this case) RelRotateCoordinateSystem method, for the axis and degrees you want to rotate. Call UpdateDraw to force the changes to be applied to the chart.
private void LinePlotSaleVolume_KeyPress(object sender, KeyPressEventArgs e)
//Rotate a negative 5 degrees about the x-axis
pTransform1.RelRotateCoordinateSystem(new Point3D(-5, 0, 0));