I'm not sure you can do that in JFreeChart.
A solution (which is not nice) is to render the chart to an image and then manipulate it (chop it up etc.) as an image, using RenderedImage, and not as a JFreeChart. Unfortunately that's going to be a bit of a pain since you'd probably want to chop at a particular place on the y-axis etc.
Brian Agnew
2009-09-07 11:56:51