Create account and pass authentication details to moodle

I am trying to have a single sign on environment from one of our house built apps to our Moodle environment.  Basically the user will authenticate to our house built app and then click a link which will point them to (something like this):

http://[SITE]/elearning/login/index.php?userid=12345&firstnm=David&lastnm=Smith&courseid=6&flag=T&session_id=1234567890

With the information in the query string I would like to do one of two things:

• Log the person into the Moodle course
• If the person doesn't have an account in Moodle, create the account with the information provided in the query string and then log them into moodle

Does anyone know if this is possible and how to do about it?

Thanks.