[pax]

Как-то так

foreach(Transform child in transform) {
     GUILayout.BeginArea(new Rect(0,0,Screen.width, Screen.height));

			GUIButton button = child.GetComponent<GUIButton>();
			if(button.anchor == Anchor.Center || button.anchor == Anchor.Right) GUILayout.FlexibleSpace();
			button.DrawGUI();
			if(button.anchor == Anchor.Center || button.anchor == Anchor.Left) GUILayout.FlexibleSpace();
		
     GUILayout.EndArea();
}