R help - May 2008 - Displaying horizontal abline levels and controlling object opacity

> Hi,
>
> I am plotting time series data, then using abline to draw a horizontal
> line through the graph (for mean, etc). I would like to be able to
> display the level at which the abline is drawn on either the left  
> (main)
> Y axis or a supplemental right Y axis.
>
> Additionally, I would like to display 1 and 2 standard deviations of a
> certain measure (rolling regression betas, in this case). But since I
> already have 2 horizontal lines going through my graph (and yes I am
> using colors and have them all in the legend), I am wondering if there
> is another way of displaying the sd-s? Maybe through rectangles with  
> low
> opacity ...
>
> Thanks in advance for any ideas/suggestions.
>
>
> Arshavir