No matter how you would do that, I won't let it detract from the new "teaser" trailer for Killzone 3. Something you can see below or over at the official Killzone 3 website. If you want to go through all the normal BS to see this trailer and such.

At first this may not look like much of a tease since it is all a pre-rendered fight scene. But what it would seem is the tease is the last little bit of the teaser; Where it looks like you might be infiltrating the Helghast from the inside. At least that would explain why the "hero" of the fight places the fallen Helghast's helmet on and dons the armor. I'm just spit balling here.