how to build DIS PDUType dissector

I'm working on wireshark v1.8.0 and was trying to understand the DIS dissectors already installed in wireshark in order to modify them however it has been a trying process. Does anyone here have some experience directly editting the packet-dis.c, packet-dis-pdus.c and .h files in order to add in further dissectors for different PDU types? Thanks in advance.