I know all the 'special powers,' like the hero abilities, and most of the extra things you see in a units command set are hard coded. SpecialPower.ini links all the special powers the units have to a certain 'Enum' in the game code, my guess in game.dat. as for the missile defender:
Code:
CommandButton Command_AmericaMissileDefenderLaserGuidedMissiles
Command = SPECIAL_POWER
SpecialPower = SpecialAbilityMissileDefenderLaserGuidedMissiles
Options = NEED_SPECIAL_POWER_SCIENCE OK_FOR_MULTI_SELECT NEED_TARGET_ENEMY_OBJECT NEED_TARGET_NEUTRAL_OBJECT CONTEXTMODE_COMMAND
TextLabel = CONTROLBAR:LaserMissileAttack
ButtonImage = SSLaserMissile
CursorName = LaserGuidedMissiles
InvalidCursorName = GenericInvalid
DescriptLabel = CONTROLBAR:TooltipMissileDefenderLaser
ButtonBorderType = ACTION
UnitSpecificSound = MissileDefenderVoiceModeLaser
End
the actual attack is hard coded, but the targetting can be changed, i think. thought of changing the NEED_TARGET_ENEMY_OBJECT, but it works for the building targeting weapons too...