I've done a lot of my own windshield replacements over the years. The only wire I've used was an old bicycle cable (brake or shifter cable). I find a place to pop it through then just saw it back and forth as you pull it through the urethane seal. I've also wrapped it around vice-grip pilers to give me some extra pull. Also having someone on the inside gently pushing outwards on the glass to keep it from re-sealing can help.
Don't remove all the old sealer from the seams, just cut it down smooth with a razor after you get the old glass out. Then throw some new black urethane sealer around the frame and stick the new glass in. Press it down gently all the way around to seal it up. I usually keep it in a dry place for at least 12 hrs. so it can cure. So far I've never had a windshield leak on me.
Just be careful when cutting the glass out as it can chip and pop out at you. Always wear safety glasses and gloves if you have some. Glasses for the person on the inside too if you have help. I've had one old windshield put up a fight and had to put my feet against it to push it out and it started to pop and crack all over the place. Tiny shards of glass are not something you want to get in your eye.
