This question is a bit of the kind of if you lose both your arms and your legs, would you still be able to move?
Offcourse you need hydraulic power to be able to move your controls.
What AhhhVC813 says is very interesting... If both engines fail due to fuel starvation, the engines will windmill, and a N1 of about 12-20% is sufficient to power the hydraulics.
And without fuel... there is no APU.
P77