I'm seeing a few people encountering installation instructions. I know reading installation instructions isn't the most popular thing in the world, but in order to correctly install this pre-release, you need to send yourself the installation SMS, as instructed below here.
Install the .sis file, and when the email setup screen appears, stop there
From your PC, go to https://email.nokia.com
If you already have a Nokia Messaging account
Select "Log in"
Enter your primary email address and password
Select "Install now"
Enter your phone number, select any device, then select "Next"
If you do not have a Nokia Messaging Account account
Select "Sign up"
Select any device and complete the simple 3 step signup process
Wait for the SMS to arrive on your device.
Select "Start", enter your password, and log in
-Davis Fields
Nokia Messaging