InputOverride.cs

public class EditorMenu
    {
        [MenuItem("Custom/Setup InputManager Asset")]
        static void SetupInputManagerAsset()
        {
            var inputManagerAsset = AssetDatabase.LoadAllAssetsAtPath( "ProjectSettings/InputManager.asset" )[0];
            var serializedObject = new SerializedObject( inputManagerAsset );
            var axisArray = serializedObject.FindProperty( "m_Axes" );

            axisArray.arraySize = 100;
            serializedObject.ApplyModifiedProperties();

            int axisIndex = 0;
            for (int joystick = 1; joystick <= 10; joystick++)
            {
                for (int analog = 0; analog <= 9; analog++)
                {
                    var axis = axisArray.GetArrayElementAtIndex( axisIndex++ );

                    GetChildProperty( axis, "m_Name" ).stringValue = string.Format( "joystick {0} analog {1}", joystick, analog );
                    GetChildProperty( axis, "descriptiveName" ).stringValue = "";
                    GetChildProperty( axis, "descriptiveNegativeName" ).stringValue = "";
                    GetChildProperty( axis, "negativeButton" ).stringValue = "";
                    GetChildProperty( axis, "positiveButton" ).stringValue = "";
                    GetChildProperty( axis, "altNegativeButton" ).stringValue = "";
                    GetChildProperty( axis, "altPositiveButton" ).stringValue = "";
                    GetChildProperty( axis, "gravity" ).floatValue = 10.0f;
                    GetChildProperty( axis, "dead" ).floatValue = 0.001f;
                    GetChildProperty( axis, "sensitivity" ).floatValue = 1.0f;
                    GetChildProperty( axis, "snap" ).boolValue = false;
                    GetChildProperty( axis, "invert" ).boolValue = false;
                    GetChildProperty( axis, "type" ).intValue = 2;
                    GetChildProperty( axis, "axis" ).intValue = analog;
                    GetChildProperty( axis, "joyNum" ).intValue = joystick;
                }
            }

            serializedObject.ApplyModifiedProperties();

            EditorUtility.DisplayDialog( "Success", "InputManager asset has been initialized.", "OK" );
        }


        static SerializedProperty GetChildProperty( SerializedProperty parent, string name )
        {
            SerializedProperty child = parent.Copy();
            child.Next( true );

            do
            {
                if (child.name == name)
                {
                    return child;
                }
            }
            while (child.Next( false ));

            return null;
        }
    }