To use, go to the overhead map and hold down ALT, RIGHT SHIFT and ~ for a few seconds. A chest will appear. It contains all the items you need to finish the chapter and you can heal your characters. To open the chest you need the correct code...they are:
Chapter 1---6478 Chapter 2---9216 Chapter 3---7702 Chapter 4---2132 Chapter 5---5052 Chapter 6---0680 Chapter 7---0194 Chapter 8---4743 Chapter 9---9995