Well said, Lilywan,
@Naarkon,
_NickName_ and Sithborg suggested that, it wouldn't be possible to do that, "Missiles Deathshot"/"Flamethrower, Thud Bug, etc" deathshot,
because 'replaces attacks' is only the attacks you can make as part of the character's activation on their turn. Thats the ruling in 'official' situations, because thats how the game was designed.
However, if you're playing houserules, and your opponent agrees,
you could home-rule that people can use replaces attack abilities when CE's grant it
It could lead to some interesting situations.