Originally Posted by
aztimm
I know to stay away from the outside shuttles, if I can.
.......
I know that B and D are connected after security (airside), but are they connected before security?
No, they are not connected outside. You can look at Google maps aerial view and you will see that. Plus I know it from experience.
If you cannot check in online, you can try the kiosk, if there is one in terminal B like there is in terminal A, where you can theoretically check in for the different airlines and theoretically scan your passport. The one in terminal A is at the very first gate that you walk to from the train before you go upstairs. Good luck.
If not, then I'm afraid you're stuck with the shuttle.