Easy.
Trigger_Always [Keys] 'Target: Start_Sound'
Target_Speaker [Keys] 'TargetName: Start_Sound', 'Noise: sounds/BLAH.wav'
Trigger_Always [Keys] 'Target: CountDown10'
Target_Print [Keys] 'TargetName: CountDown10', 'Message: 10'
Target_Delay [Keys] 'Target: CountDown9', 'TargetName: CountDown10', 'Wait: 1'
Target_Print [Keys] 'TargetName: CountDown9', 'Message: 9'
Target_Delay [Keys] 'Target: CountDown8', 'TargetName: CountDown9', 'Wait: 1'
...
Target_Print [Keys] 'TargetName: CountDown0', 'Message: 0'
Target_Speaker [Keys] 'TargetName: CountDown0', 'Noise: sounds/BLAH.wav'
Trigger_Always - Activates its Targets when the map loads.
[Keys] - With the entity selected hit 'N', type my listed 'KEY: VALUE's in to the corresponding fields, hitting enter/return after typing the value for each one (It'll then be added to the list above).