No
The random values for mob spawn times and locations are not taken from the world seed.
Source: My own experimentation. This is super-easy to verify with a super-flat world.
I'm not sure if this would fit your needs, but you could try the spreadplayers command.
Despite it's name, it is also capable of spreading mobs, with the in Minecraft 1.8 newly introduced @e selector.
/spreadplayers x z distance radius false @e[type=Creeper]
x z: The coordinates of where the mobs should go.
distance: The approximate distance the mobs should have.
radius: The radius of the area in which the mobs are spread (not a circle, but a square).
false: Just leave this at false, it is intended to respect teams when spreading players.
@e[type=Creeper]: The mob selector, the type=Creeper is very important. You can write other mobs name in this, but do not leave it out, as that would spread itemframes, signs, minecarts... And that would be a mess.
Of course this only spreads the mobs, but you have to summon them first, but i think that is no problem, just use command blocks with /summon Creeper x y z and you're good to go ;)
Best Answer
Perhaps you could try placing daylight sensors and switching them to night mode, then linking that to a command block that spawns a custom mob.
You could place that contraption in multiple places around the map.