Your correct about the chart swallowing the gestures. It isn't possible to have the chart responding to panning gestures and to also have your scroll view to receive those gestures, it doesn't really make sense from a usability point of view. This is similar to how a scroll view nested within a scrollview would work.
What you can do (which is what I think you were asking) is disable the panning gesture recogniser. You can do this by like so:
chart.gesturePanType = SChartGesturePanTypeNone;
If you need to keep the panning functionality, then you can't really do the above. In that case, we find that adding some kind of handle for the user to drag works quite well.