What is the best way to set up Time Traveler on someone's computer?

Wait until the victim steps away from their desk, then quickly run Time Traveler from a USB drive or a pre-copied file. The program starts working immediately and runs invisibly. When the victim comes back, they will notice the clock showing the wrong time and try to fix it -- only to see it change again moments later. For maximum confusion, set a longer interval so the changes happen gradually and are harder to pin down.