you do not need a capo for this. You sight down the neck as though you were aiming a rifle and the neck should have a ever so slight concave bow. Look down the bass side and the treble side and compare the relief from each side. If your neck has a twist the relief will be noticeably different between the treble and bass sides. In this case you want to split the difference in how much to tighten. The heavier the strings and or how hard you play will requires more relief. Lighter strings and lighter attack require less relief. Tightening the rod takes out relief and loosening adds relief. Righty righty-lefty loosy. Try tightening your rod 1/4 to 1/2 turn (clockwise is tighter) then sight down the neck again. If the nut on your rod is loose tighten until it snugs up then tighten from there. The saddles should also match the fingerboard radius.