Draw a Horizontal target line on bar chart

I am trying to reach out to crystal report gurus for the following problem, I am relatively new with crystal reports and would really appreciate if you could provide a solution or point me in the rite direction.

I am working on a project which requires to show various charts on an .aspx page. (.net 2.0). I am using CR10.2.36, the one that comes with VS2005.

My problem is I need to add a target line on a bar chart, e.g.

I have (Y)years and (X)Examscores, I need to put a line (target line) on the Exam Scores.

100% |

(X)Score |

|

0% |__________________________

2001 2002 2003

now this target line should move up or down on click of a button or a .net slider control (which would be somewhere on the page).

So I guess I need to add the target line to the bar chart programmatically after the chart loads.

I am able to load the chart correctly but I am not able to think of a way to add the target line and there seems to be not a lot of help out there.

I appreciate your time and help

Thanks

rohan