It is very easy at EWR -- no cab involved!! Go to the Bus Stop and the very last lane is the FedEx Stop. Wait tims is approx. :20 minutes (max). Depending on the time of the day you will see other FedEx employees. When the FDX bus arrives (and it does look like a school bus), board and kindly inform the driver that you are also going to EWR Ramp.
Arriving at the Ramp you will be sent through security, required to present ID/sign in, escorted through the maze we call EWR, and delivered to the jumpseat area. Free Coffee.
The flights you are talking about are on the 727 (I believe), so it may be a little noisy.
Good Luck.