I also use the Wheeler tool, and it works pretty darn good. But, if you don't want to buy a tool just level the action in a vice and set a piece of paper out with crosshairs drawn on it, making sure both lines are level/plumb. Then just fiddle with the scope until your reticle lines up with the lines drawn on the paper. Just make sure that the action and target remain level throughout the process. Also, the further away the target the better.