Here's one way of going about it:

var currData, currDataSource, doGeneration;

    doGeneration = function() {
        var num = 30,
            data = [],
            curr = 10;
        for (var i = 0; i < num; i++) {
            if (Math.random() > .5) {
                curr += Math.random() * 2.0;
            } else {
                curr -= Math.random() * 2.0;
            }
            var rad = Math.random() * 100.0;
            data[i] = {
                Label: i.toString(),
                Index: i,
                Value1: Math.round(curr * 1000.0) / 1000.0,
                Value2: rad,
                Value3: (rad / 100.0) * 20
            };
        }
        currData = data;
        currDataSource = new $.ig.DataSource({
            dataSource: currData
        });
    }

    doGeneration();

    $("#chart").igDataChart({
        width: "700px",
        height: "400px",
        dataSource: currDataSource,
        axes: [{
            name: "xAxis",
            type: "numericX"},
        {
            name: "yAxis",
            type: "numericY"}],
        series: [{
            name: "series1",
            type: "scatter",
            xAxis: "xAxis",
            yAxis: "yAxis",
            xMemberPath: "Index",
            yMemberPath: "Value1",
            markerTemplate: {
                measure: function(measureInfo) {
                    measureInfo.width = 10;
                    measureInfo.height = 10;
                },
                render: function(renderInfo) {
                    var ctx = renderInfo.context,
                        radius;
                    
                     var data = renderInfo.data;
                     var name = "null";
                    
                     if (data.item() != null) {
                         name = data.item().Value1.toString();
                     }
                    
                     var height = ctx.measureText("M").width;
                     var width = ctx.measureText(name).width;
                    
                    if (renderInfo.isHitTestRender) {
                        ctx.fillStyle = renderInfo.data.actualItemBrush().fill();
                    } else {
                        ctx.fillStyle = "black";
                    }

                    var halfWidth = width / 2.0;
                    var halfHeight = height / 2.0;
                    var x = renderInfo.xPosition - halfWidth;

                    var y = renderInfo.yPosition - ((halfHeight * 2.4) + 5.0);
                    var scatX = renderInfo.xPosition - 5.0;
                    var scatY = renderInfo.yPosition - 5.0;
                    
                    if (y < 0) {
                        y += (halfHeight * 4.0);
                    }

                    if (renderInfo.isHitTestRender) {
                        ctx.fillRect(scatX, scatY, renderInfo.availableWidth, renderInfo.availableHeight);
                    } else {
                        ctx.textBaseline = "top";
                        ctx.fillText(name, x, y);
                        
                        ctx.fillStyle = renderInfo.data.actualItemBrush().fill();
                        if (data.item().Value1 > 5.0) {
                          ctx.fillStyle = "red";                                    
                        }
                        ctx.fillRect(scatX, scatY, renderInfo.availableWidth, renderInfo.availableHeight);
                    }
                }
            }}],
        horizontalZoomable: true,
        verticalZoomable: true,
        windowResponse: "immediate"
    });

-Graham