Are you confident that it is repairable?
If so then go at it just a little at a time (start with quarter turns perhaps)
Look for where it is out of true and tighten the corresponding opposing spoke AND then tighten the two same side spokes on either side a very little bit too.
IE:
Say, if you have a drive side spoke that needs more tension, tighten that one a half turn, then tighten one drive-side spoke to the left and one drive-side spoke to the right a third of a turn; just to help keep one from taking too much of the grunt.
Also, feel free to loosen the spoke opposing the one you are tightening too (but a very very little amount)
I don't know if this will help or not. I am not sure how much you already know, and am typing this clearly is difficult. It is pretty intuitive once you understand which way to tighten/loosen them. So I guess everything I said above really just boils down to "DO IT SLOWLY" as it is was too easy to make things worse.
Try putting a drop of T9, or whatever lube, on each of the spoke nipples.
And if you feel like you are having to wrench too hard, you probably are. Nipples do round off (thus killing all chances of trueness) and having your face next to spoke that breaks if you over tighten it sucks.
If the rim is really bent you may quickly exceed safe spoke tension trying to get 'er true.
Sorry, a bit tangential tonight. Good luck and I hope this helps.
