13 Dec 2011 13 Dec 2011
The DLC loader is in Ch4: Under the Shadow.
Since it's near the end of the chapter I suggest restarting from checkpoint when there is one Locust left in the area because his death creates a new check point and you would have to start from the beginning again.
This can be done on any difficulty on Arcade or Campaign, but you CAN'T have the Instagib punch modifier on.
*If it worked for you with the modifier that's fine but it wouldn't for myself and I don't recommend it.