Use java to loop over some dfc code like this :
IDfUser dfcUser = (IDfUser) getSession().newObject("dm_user");
dfcUser.setUserName("username");
dfcUser.setUserLoginName("username");
dfcUser.setString("user_source","inline password");
dfcUser.setString("user_password","somepassword");
dfcUser.setString("user_os_name","username");
dfcUser.setString("description","new user description");
also, you could use a tool like Qit : Qit by Qtree
You can develop your own plugins, I am currently developing one to duplicate a user.
These plugins will appear on the website soon.