You must identify how the EStop is exposed by the MPG. There is nothing about EStop in the mpg.hal file above. You may have to consult the MPG manual. It may be exposed as a signal you can add to the mpg.hal file, or it may only be exposed as two or four wires (which you must wire as a hardware-EStop.)
Your .hal file also does not have any entries for EStop. You'll need to use the .hal command 'net' to link it. How the 'net' command works:
linuxcnc.org/docs/2.5/html/hal/basic_hal...#_net_a_id_sub_net_a
Once you figure out how your EStop button works, it would be best to find a similar setup:
duckduckgo.com/?q=linuxcnc+estop+net
