Hey, there is a thread for a packerlogger but everything is in german.
A easy explanation is, you download the packetlogger and a program that can inject a DLL file, we call them injector. When you have both, then you start the program and inject the packetlogger DLL file into the nostale process.
With the packetlogger you can catch packets that are flying around between client and sever. You may to change the information that are in the packets and if you are lucky, then you can find a hack or something else