The outputChart doesn't have a "yaxisLabels" attribute.
I looked at the JCharts API, and found that there isn't any way to set Yaxis labels as literal. The Y-aix labels are generated by the Chart API on the bases of provided data. I think that is why we didn't add "yaxisLabel" attribute on component.
The only thing can be done on yaxis is to set user define scale by defining starting value and value of the increment, in addition to that you can tell how many generated item should be display on a chart by default they are 5. Or you can force to show dollar sign or hide or show comma.