I think I'm gonna go with the Necron knockoffs.

How would I make their stats?

You could make them as easy or difficult as you'd like, though I'd make sure you give them at least Machine (4). It really depends on how powerful your party is in combat. If they're on the low end, just add Machine(4) to regular guys and leave the rest to discription. If they're powerful, consider going up to Machine(6), giving them built in armor, Unnatural Toughness and/or Strength, etc.

There might also be different 'Grades' of badguys. The armsmen or officers might have much more advanced (ie powerful) bodies then the regular crewmen. If you want to get the traditional bossfight in, consider installing some real Necron tech in the captain, or his Arch-Militant. Could make him an ex-Rogue Trader if you want to really drive home the irony/moral lesson.

Hmm.

I'll probably have the main bad guy be made out of the living metal that Necrons are made of.

But that leaves the common enemies.

Screw it, I'll use the hired gun profile from the core rulebook, remove Fellowship, add Machine (4), and give them an energy weapon with the stats of a Boltgun.

That sound good?