Batch add users

[autolab]

Using 3.8.2

We are running a free 30 day trial promotion. I would like to send users a username/password and have them be able to jump right in without having to register.

Is there a utility to upload and add users in a batch?

I am proficient enough in PHP and mySQL to work with the database.

Can I simply add them to the user file? If so how is the pw encoded?

Thanks