Hi Chris,
You can use set the StartAngle and SweepAngle on a CircularScale, to alter what portion of the circle the ranges, pointers, etc in the scale use. We don't currently have a built-in frame for 90 degrees gauges like you are describing.
I've marked down a TODO item to add built-in support for these types of frames in a future release. It is possible to render your own background or use a custom Geometry. The former is accomplished by overriding CircularGauge.OnRender and adding your own custom drawing code. The latter is accomplished by setting the CircularGauge.BackgroundGeometry property and setting CircularGauge.BackgroundType to CustomBackgroundGeometry.
