Ok so please correct me if I am wrong... so basically you need to convince an admin (admin of the server you want op from) to connect to your server (for example 126.96.36.199:25565) is that correct? So when this person connects to your fake "server" he will than get the "Outdated Client"-Msg and on the real server you're still on you will recieve the OP ?
So here is what I did:
1. I set up a simply craftbukkit server.
2. copied the files attached in this thread into my server folder. (start.bat into main server folder and the SessionStealer.jar into the Plugins folder)
3. started start.bat afterwards fill in the desired server IP I want OP on, and it's Port. Fill in the rest of the gaps obviously...
Now the requirement ?:
4. ask an admin on that desired server to join my "server"
5. if all goes good and this admin connects to my "server" I'll get OP on his server?