how do i add extra series to a hi low open close volume chart?

[sicoxic]

hi thanks for reading my post.

I have a chart that has data loaded into it as the high low close open and volume. How do i add an extra series that is not the part of the candlestick or any other chart type and is just a line graph plotted on to the graph. I am doing this as i want to see for instance another commodities close price against the one in the candlestik chart. I dont want to chart this onto another axis or pane too.

 

Any pointers would be thanked.

 

Paul