User want to drag the series point as well as series line(whole series line) in any direction, so the user can move the series where he want, please refer the below URL, where user can move the series point in vertical direction only, likewise the user want to drag the series point as well as series line in any direction, so he can set the threshold  limit where he want by using the custom series and analysis the chart against his threshold limit

http://jsfiddle.net/SpaceDog/QsKaJ/1/