User terms module is best module for user taxonomy terms you can have in drupal 6. Mostly it works as it should and there is no lack of functionality. However, if you want to bulk change user terms, you are out of luck, VBO doesnt work with it so you have to do this manually. I created a query to change, well to add many terms to users, all user who don't have particular term to have it after query.
insert ignore into term_user (uid, tid) select uid, 372 from term_user where not tid=372so this add to all users tid=372 (which is tid of basic member) and this way you can mass edit user data. If you want to update/change data and not add new terms, use Update instead.