You can do it by turning off the 'status bit' decoding, but then you'll need to put the separate TG's in your scanlist...Using Toledo as an example...
80 is EMS channel 2. If you have that in your scanner, in the default mode, you'll get all transmissions whether emergency, patched, or whatever. However you will not know if the emergency is pressed.
If you turn off status bit, then put 80 and 82 in your scanlist (and set 82 to beep alert, and alpha tag of "EMERG - EMS"), you'll see conversations on 80 during normal mode and then hear a beep and see "EMERG" when they transmit an emergency.
I use that also for groups I don't normally monitor - yet want to know if an emergency is issued. Police-North is 656, so I put 658 in the scanlist ONLY and I never hear a thing unless the officer presses EMERGENCY on his radio.
Rob