I walk down S. Firehouse Rd. toward the employee lot. There is always an open door at the fence just before the old entrance to the lot and I wait for the employee shuttle. They drop you off between the terminal and the new rental car facility no questions asked. So far so good.
Depends on how long you wait for the bus. Longest it has taken for me is 15-20 minutes (ramp to ticket counter) but I'm usually doing this during normal daylight hours.