Additional data value for callbacks

I have multidimensional data, let's say just three dimensions: X, Y and Z. The scatter plot only allows me to specify the "x" and the "value", meaning the x and y axes of the resulting plot.

Is there a way to instead specify "x", "y" for the data values used as axis positions and "value" as additional value used for coloring or size of the points?

I tried specifying a (binary) color change like this inside the data block:

```
color: function (color, d) {
return d.value && d.value < 10 ? d3.rgb(255,0,0) : color;
}
```

but I have no idea how to get additional data in there. d only has the variables x, value, id and index, for example: {x: 12345, value: 23, id: "test", index: 345}. Data originally existing in the json data I supplied to C3 is not included there.