Yes, you have the option of connecting an external pushbutton.
After you have disconnected the device from the power supply, first remove the cover of the device so that you can see the electronics. You can connect a pushbutton between DOOR and GND to the terminal labeled DOOR-GND-EMRG.
Note: The jumper between GND and EMRG also remains connected. A wicket door contact or emergency off can be connected at this point, for example. 