My recommendation would be forward each and every adduser request to the guy who owns the server and ask him to do it because you don't have the necessary tools/privs. Be sure to also CC the person who requested the new ID, so he/she knows the ball is in that guy's court and that you're not the bottleneck.
Seriously, as an outside observer, it seems to me that the situation you've described is that an employee (meaning you) has been given the responsibility to perform a certain task, but that the employee's managers are refusing to give him the tools he would need to do the job. That's an un-winnable situation, and the only 2 outcomes to resolve it are to either reassign the task to someone who does have the tools (the other guy), or to provide you with the necessary tools (meaning giving you root). If the latter option is not a possibility, per your post, then that leaves only the former.
In any event, I totally agree with 320mb; personally I would consider adding new user accounts to be the responsibility of root, and any steps taken to defeat these built in security measures would be ill-advised IMO. -- J.W.