Chances are that you'll be fine without a torque wrench. I use a torque wrench when the torque specs are supplied. I love it when manufacturers put the torque specs on their parts, especially when it's lazer etched. What a nice touch! Start by just snugging the bolts and checking to see if the bar can twist or the stem can rotate on the steerer tube. If it does, just tighten it a tiny bit more and check it again. Continue until you are confident that the parts aren't going to slip while you are riding. As long as you get everything secure and don't ruin anything you'll be good. If something is still slipping ,and you strip a bolt or something the next time you turn it a touch, then there was a problem no matter if you used a torque wrench or not and the torque wrench wouldn't have solved it.