Edit in JSFiddle

var data = [{
  "Word": "Hello",
  "Awesomeness": 3000
}, {
  "Word": "Pie",
  "Awesomeness": 2000
}, {
  "Word": "Chart",
  "Awesomeness": 1000
}, {
  "Word": "With",
  "Awesomeness": 500
}, {
  "Word": "Labels",
  "Awesomeness": 400
}, ];

//this is a regular pie/donut chart with legend
var svg = dimple.newSvg("body", 300, 200);
var chart = new dimple.chart(svg, data);
chart.addMeasureAxis("p", "Awesomeness");
var ring = chart.addSeries("Word", dimple.plot.pie);
ring.innerRadius = "50%";
chart.addLegend(0, 0, 90, '100%', "left");
chart.draw();

//this chart will have radial labels
var svg = dimple.newSvg("body", 300, 200);
var chart = new dimple.chart(svg, data);
chart.addMeasureAxis("p", "Awesomeness");
var ring = chart.addSeries("Word", dimple.plot.pie);
ring.innerRadius = "50%";
ring.afterDraw = function(shape, data) {
				var g = svg.select("g");
        //find the center of the pie
				var grect =  g.node().getBBox();
				var gmidx =  grect.x + (grect.width - 7)/2;	
				var gmidy =  grect.y + (grect.height - 7)/2;
				var radius = (grect.height - 7) / 2; 
        //find the center of the pie-part
				var srect =  d3.select(shape).node().getBBox();
				var smidx =  srect.x + srect.width/2;	
				var smidy =  srect.y + srect.height/2;
        //get the direction:
        //the parts are arranged around the center as origin (0,0)
        //so the direction is simply the mid point of the pie-part
				var dirx =   smidx;
				var diry =   smidy;
				var norm =   Math.sqrt(dirx * dirx + diry * diry);
				//normalize the direction
				dirx /= norm;
				diry /= norm;
        //multiply direction by radius to find placement for label
        //get two points: where to put label, and where to draw a line
				var x = Math.round(gmidx + (radius + 25) * dirx);
				var y = Math.round(gmidy + (radius + 15)  * diry);
				var xOnPie = Math.round(gmidx + (radius+4) * dirx);
				var yOnPie = Math.round(gmidy + (radius+4) * diry);
        //append label
				var node = svg.append("text")
		        	.attr("x", x + ((dirx > 0) ? 5 : -5))
		        	.attr("y", y + 3)
					.style("font-size", "12px")
		        	.style("font-family", "sans-serif")
		        	.style("text-anchor", (dirx > 0) ? "start" : "end")
				    .style("fill", "black")
					.text(data.aggField[0]);
        //append line
				svg.append("line")
				    .attr("x1", x)
				    .attr("y1", y)
				    .attr("x2", xOnPie)
				    .attr("y2", yOnPie)
				    .style("stroke", "#e0e0e0");
			}
chart.draw();