Broken pulley bolt-am I screwed?

[blue thunder]

I just finished doing the knock sensor replacement and was tightening down the bolt on the pulley for the alternator. The bolt just broke right off. I may have overtightened it plus it being twelve years old and getting taken apart a lot lately. I went to my auto parts store and got another bolt close to the same diameter and a matching nut. Once I put it on though I realized I can't hold both ends to actually tighten it. The inside of the bolt is hidden and blocked off. Will the OEM part only work for this? Any suggestions or related experience greatly appreciated. I am stuck and my local in town dealer is a bunch of crooks and I will have to get a tow 25 miles away.


Mike