To sniff the packets between client and server you need to edit either the connect.ini or the connects.ini.
Change the IP to 127.0.0.1
Now create a program that listens on 127.0.0.1 + the port given in the .ini.
If you get packets in you need to create a client in your program.
This client connects to the real server and sends the client incoming packets to it.
And the your client sends the server incoming packets to your real client.
It isn't that difficult. I have a base which can be used for nearly every thing