I don't quite understand your question.
Do you mean user information through the interface itself or all users through the API?
If the former, I think that command is only available through the API. If you wanted to get a list of databases and ftp accounts of all users at the same time you could have your script collect a list of all users and then run the api command on each user one at a time.
Or if I am way of base in what your trying to do, let me know