Does it need to be a pie chart? A bar chart would make it much easier to match the legends to the values since they'd line right up. It's also easier to compare bar lengths than to compare slice areas. Doesn't solve the scrolling problem unless they all fit, though. It's interactive, though, so you could use an "others" bar, and click through it to get the smaller values. Just a thought since I don't know how to do what you're asking in any simple way.
It does seem like QlikView should be able to do that, but I couldn't figure it out. So I faked it. This is two charts made to look like one. The pie chart has no legend. Then there's a bar chart that has ONLY the legend. Stick them together, make sure they sort in the same order and have persistent colors, and I think it'll work.