God has used in the past folks against their will. For who can resist His will? By that, I mean if God wants to use you, He'll create circumstances in a person's life that they have no choice but to obey or their life will just plain out suck. This is one example of His Sovereignty. This doesn't mean God is a bully, but He can do whatever He wants with those that are His.
At the same time, we still have a will. Otherwise, we wouldn't do the stupid stuff we do to disobey God. He still gives us a choice. But I do believe if He has an agenda, it will get done irregardless of whether we want it to happen or not. We still have the will to disobey even if He brings circumstances into our lives that make our lives miserable.
Take anyone in scripture and look at how they were called by God. God's will shall be done. If it isn't accomplished thru our obedience, He'll use someone else and we'll be held accountable. We still have a will to obey or disobey.
With that said, God can save anyone who comes to Him by the Gospel of Jesus Christ. God can create circumstances in a person's life that convict them, but either way, God won't save someone who continues to reject Him. Can He? Sure, I believe God can make a person's life so miserable that they have no choice but to obey and believe. How could they not? Why would anyone desire to live a life of hell? But ya know what, they do it all the time. But I do believe there are those who have hardened their hearts until the end.