The lot 10E is no way walkable to the terminals...esepcially the US Air Termina. I mean it could be done, but it would take a LONG time. There are 3 bus loops from the lot - the Short, Long and East. The short goes to AA, the Long to the Central Terminal and the East to Delta and US Airways.

The lot just used to have a rent a cop that you could show a Amex card to and get in - however, the Port Authority recently went high tech and it uses a magnet type card to get in with gates and all. Without that card they dont let you in at all - its a pain in the ass!

Good Luck!