[flexcoders] Charting: Adding a horizontal line

[flex_coders]

I'd like to add a few horizontal lines to my area chart, a solid line
to indicate where the average is (y=avg) and two dashed lines for +/-1
std devs away. is there a simple way to add a line to the chart
indicating y = [some value] or rather do i need to need to
programatically just draw the line?