>>151
AlertDialog#show以降でとってきてみて

例
AlertDialog.Builder diagBuilder = new AlertDialog.Builder(this);
diagBuilder.setTitle("hoge");
diagBuilder.setMessage("hogehoge");
diagBuilder.setPositiveButton("button", null);
AlertDialog dialog = diagBuilder.create();
dialog.show();
((Button)dialog.findViewById(android.R.id.button1)).setTextSize(30);