Powerless doesn't mean you can't do anything about it. Powerless simply means that you can't change the fact you are an addict, in the same way that someone with diabetes can't change that fact either.
Does this mean a person with diabetes is doomed to die? No! But instead of fighting diabetes, he needs to learn what WORKS for a diabetic!
So again to sum up: Powerless is referring to the disease and not to the person's ability to help themselves.
Also, powerlessness implies a combination of two things.
1) Once I start, I can't stop. No matter how much I know it will kill me, I will keep going.
2) I must stop. It is poison for me. It will kill me.
Recognition of these two things FORCES us to come to rely on Hashem completely because we have no way out. We are stuck between a rock and a hard place. And when Hashem sees that we honestly realize that without Him we are finished, He makes miracles for us. (As Chazal say "Ain ben David ba ad sheyomru ain lanu al mi li'hisha'en ela avinu shebashamayim".)
When we are faced with a test and say "I'm powerlessness" we mean to say, "If I start, I will not be able to stop. And it will kill me."
It is analogous to a drunk getting into his car and muttering to himself, "I know I am drunk. Once I start driving on the highway, I won't be able to stop. And I will likely get killed - or kill others".
Powerless makes us realize we CANNOT AFFORD TO LUST. We can't afford to get into the lust car. We are drunk and we will soon be driving down a road to gehenom!
Once we have the recognition of powerlessness that incorporates both of these aspects, we force ourselves to make the right gedarim. We learn how to do our best to avoid the first drink, and we learn how to give over our will to Hashem to save us from this "death".
