In addition to the information in the COCO documentation, newcoco has one additional feature. If you give the command line argument -pt when you run coco your resulting parser will produce parse trees of the input programs.

Thus instead of running coco with
java -classpath .;newcoco.jar Coco.Comp GCL.ATG

you use the following instead to get the parse traces
java -classpath .;newcoco.jar Coco.Comp -pt GCL.ATG