look into damage.gsc, and there for dofinalkillcam.
i dont know how the mod works, but you have to check if the mods game-ending-logic is fullfilled with every kill. Once it is , simply set some variable to true (for the attacker). Put this variable in the if statement of dofinalkillcam, instead of its orginal statement.
You cannot check for game end via waittill("enemy_killed"), since this will arrive too late for the killcam to show on game end, so you have to check for it in playerkilled_internal, or callback_playerkilled.
It's not hard, but you gotta know what you do :P