the elevation knob covers the total RANGE of adjustment. turn the knob all the way down till it stops. do not overtighten it. then turn it in the opposite direction until it stops again (resistance is felt) being sure to not completely unscrew it, KEEPING an accurate count on the number of turns the knob makes. Divide that number by 2, then screw the knob down by the number calculated. that should put the reticle at the halfway point in it's range of travel. this should result in your shots striking pretty close to the center of the target if all other things are in spec. repeat the process with the windage knob. theoretically you should now have the scope set at mechanical zero, ie the point where the reticle erector is halfway between the left and right and up and down extremes of adjustment. from here mount the scope, bore sight it, and zero as normal. If there is a screw in the CENTER of the windage and elevation knobs, loosen it a little if you can rotate the marked scale (the part with the white numbers on it) so that the hash mark correlating with the Number O is lined up with the line or nib that marks a reference point. if you can do this then you now can count the number of clicks up or down when you make adjustments for distance, and then be able to return to your baseline zero whenever you want. it may be that the turret is spring loaded and you can simply pull up on them to align the 0 with the indicating mark.
If you can take a pic or two showing me the turrets, caps, and or adjustment knobs on your scope I will try to walk you through the process if you are interested feel free to im/email if need be.
http://abousainc.com/ATsystem.htm
try this web page for more assisstance as well.