YOu can do this easily by saving the query in the admin section (that's all the old mod did was auto fill in this query.
SELECT COUNT(*) as total,U_StyleSheet as style FROM w3t_Users GROUP BY U_StyleSheet ORDER BY total DESC
Go to Control Panel -> Database Tools
Click on SQL Command tab
Enter it in the box
Click Save
Then it'll appear on the list below, you can use whenever you wish to see the results.
