Currently neither of these is possible, though you can test against "has_surrendered" for enemies and "if_player_is_targeting" for players. I hope the ability to add custom transmissions is available soon.
"Damn the torpedoes! Four bells, Captain Drayton!"
(Likely actual words of Admiral David Farragut, USN, at the battle of Mobile Bay. Four bells was the signal for the engine room to make full steam ahead).