Is it possible to integrate a new chart?
Yes. You can do a tight integration in which the charts will start appearing in the drop down list of Adhoc. You can refer to http://www.helicalinsight.com/technical-guide/chart-type-in-chart-list/ to learn how to do the same. Otherwise VF can also be used for integration of a chart. For VF goto http://www.helicalinsight.com/technical-guide/how-to-add-vf-file/.