[Solved]-D3 line chart axis text labels in multi line-d3.js

I'd do it after generating the axis:

        svg.append("svg:g")
          .attr("class", "x axis")
          .attr("transform", "translate(0," +height + ")")

          .call(_config.xAxisGen)
          .selectAll('.x .tick text') // select all the x tick texts
          .call(function(t){                
            t.each(function(d){ // for each one
              var self = d3.select(this);
              var s = self.text().split(' ');  // get the text and split it
              self.text(''); // clear it out
              self.append("tspan") // insert two tspans
                .attr("x", 0)
                .attr("dy",".8em")
                .text(s[0]);
              self.append("tspan")
                .attr("x", 0)
                .attr("dy",".8em")
                .text(s[1]);
            })
        });

Updated example.