New Post: extending the TableEditor Plugin

So you want to show your own form instead standard attributes form? You can show it in your plugin instead calling layer.ShowAttribute(). It is the easiest way.

There is another, but a bit more complex way - layer.ShowAttribute() internally uses Legend.SharedEventHandlers.FeatureLayerActions which has method ShowAttributes(). So you need to set Legend.SharedEventHandlers.FeatureLayerActions with your own implementation.