James
I don't know if this is possible, but in general what i do in this case is the following:
- open excel with this chart / work in progress
- start Macro Recorder
- do whatever stuff i need ( i.e in your case draw that line )
- stop Macro Recorder
- check the newly generated Macro code
- implement that code through automation ( it's really similar )

HTH
Jaime

>Having had remarkably good success getting Excel automation to work in a short period of time (thanks, Marcia, for your sample automation form!), I find that there's one last thing I'd like to do with my line chart.
>
>I have a rather simple line chart, with data over the last twelve months (sales, system-generated forecasts, and manual-override forecasts, if any) as well as the forecasts for the next 8 months -- 20 months of data in all. What I'd like to be able to do is to differentiate between the historical data and the forecast data -- perhaps a vertical line to separate history from forecasts, perhaps a different background color for part of the plot area, or something else?
>
>Is anything like this possible?
>
>TIA