PS CS5 Shape Tool Hexagon Corner Smoothing

For the love of it I simply cannot figure out how to change the "corner radius" for the shape tool's polygon tool.  I set it to 6 sides and with SMOOTHED CORNERS off, it creates a hexagon as expected.

But if I turn on SMOOTHED CORNERS, it almost makes a circle, the corners are excessively rounded.  I see no option to control how smoothed/rounded these corners are.

When I lower this to 3 sides, I can see PS is heavily rounding the corners.  At this point, I simply don't think there's an option to do what I want here.  I know in AI, you can hold the arrow keys to add/remove corners and increase/decrease rounded corners, but PS CS5 doesn't seem to support that.