void CBCGPChartVisualObject::SetDataPointLegendLabelText	(	const CString &	strText,
		int	nDataPointIndex,
		int	nSeriesIndex = 0
	)

Sets custom legend label text for the specified data point.

Also you have to enable displaying data points in the legend (for some chart types like Pie it's enabled automatically):

Copy

CBCGPChartSeries::m_bIncludeDataPointLabelsToLegend = TRUE;

CBCGPChartDataPoint::m_bIncludeLabelToLegend = TRUE;

// Usually you don't need to set this flag, it's TRUE by default

Of course, the series also must be included in the legend:

Copy

CBCGPChartSeries::m_bIncludeSeriesToLegend = TRUE; // TRUE by default.