In addition to the Emergency notch built into the engineer's automatic (or train) brake, there is an emergency brake switch at the conductor's position. This switch is replicated in the G-TraX P42DC cab. When you hit the switch it calls RW's internal EmergencyBrake control. The core software then places the automatic brake in Emergency, sets the reverser to neutral, and zeros the throttle. I'm using a combined power handle (RW control name: ThrottleAndBrake) of which the throttle and dynamic brakes are slave controls. The EmergencyBrake control does not affect a T-A-B control so I added a line of script to reset it to Idle position.

At the engineer's position there is a control button labeled "Main Engine Emergency Shutdown." When you tap this button I scripted it to call both RW's internal EngineStop control and its EmergencyBrake control.
I don't know how realistic any of this is.
By the way, the labels on the head end power (HEP) control panel, the one just to the right of the Emergency Brake Valve, are mostly unreadable in my photos. If anybody knows where I can get a good clear image of one of these panels I'd love to get hold of a copy.