alertdialog、button enable、disableの設定方法

次のようになります.

Builder builder = new AlertDialog.Builder(getSherlockActivity());		
		builder.setTitle("test");
		builder.setPositiveButton(R.string.rating_continue,
				new DialogInterface.OnClickListener() {
					public void onClick(DialogInterface dialog, int whichButton) {
					}
				});
		builder.setNegativeButton(R.string.wispr_cancel,
				new DialogInterface.OnClickListener() {
					public void onClick(DialogInterface dialog, int whichButton) {
						/* User clicked cancel so do some stuff */
					}
				});

		AlertDialog dialog = builder.create();
		dialog.show();
		dialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(false);

注意:
dialog.getButton(AlertDialog.BUTTON_POSITIVE).setEnabled(false);