How to define the "hover" function?

Hi, I'm trying to create a graph similar to this example (with column hover.)

Viewing the source of that page, I see these lines of code:

. . .

fin2 = function () {
    var y = [], res = [];
    for (var i = this.bars.length; i--;) {
        y.push(this.bars[i].y);
        res.push(this.bars[i].value || "0");
    }
    this.flag = r.g.popup(this.bars[0].x, Math.min.apply(Math, y), res.join(", ")).insertBefore(this);
},

fout2 = function () {
    this.flag.animate({opacity: 0}, 300, function () {this.remove();});
};

. . .

var c = r.g.barchart(330, 250, 300, 220, [[55, 20, 13, 32, 5, 1, 2, 10], [10, 2, 1, 5, 32, 13, 20, 55]], {stacked: true, type: "soft"}).hoverColumn(fin2, fout2);

But I have no idea how to specify the "hoverColumn" function when creating the chart in Drupal.

Any suggestions or even a sample code would be very appreciated. Thanks! :)