Ok I figured it out. It was simple and mentioned in Document under another section which is bit confusing.
I am mentioning it here for others if they come here wondering about this topic.
Please follow
http://support.softwarefx.com/jChartFX/api#web_htmls/seriesattributes_volume.htm
http://support.softwarefx.com/jChartFX/api#web_htmls/seriesattributes_volume.htm'>Regards
Anurag