bar/line stacking

[khazeit]

Couple questions,

How can I program eviews to combine a stacked chart and a line chart?

For instance:
graph.bar(s) x1 x2 x3 y

x1 x2 x3 when summed together = y, but would like to show them as a stacked bar chart, and have y drawn as a line chart to show the sum of them all. Is this possible?

Thanks!