You can't track one guy, you need to track everyone, or nobody.
Xerox Standard accounting is what you want.
I purchased the C-75 new 2 years ago, it shows as one of my installted options "Job Based Accounting Service" how do I set it up? I have added another user on the network and need to know how much usage the person does or is there a way to issue a password for them to log in/out which will track there usage?