Please, check out AnnoCultor from Subversion, and look at the demos (directory demos) to see how a custom converter can be built and executed.
JDK 6 is required.
In the demo examples converters are located in profile/profile.xml and working directories are assumed to be called work (you may choose any other). To run a demo you need execute the following command from the directory of the demo (e.g. ICN convert.bat):
convert
Please, refer to file pom.xml (e.g. ICN pom.xml) for more details on how it works.
After a run you should get a lot of console messages and, if lucky, some files in the outputDir set in the converter.