Sorry just found it
You can set up a layout with global fields for making hanges to account name, password and/or privilege set. Script built from steps taken from the "account" section of the list of steps down the left hand side of the script editor can then make the specified changes. You can design this with just the capabilities that you need and this script can include updating a users table with account name and other data, though I wouldn't store passwords in such a field unless absolutely necessary. (And I can't think of a reason why you really need to store the passwords...)
You'd set such a script to "run with full access privileges" to enable users who do not have a "full access" privilege set to run them.