I need to register 12000 presign ups as active users.

Would anyone know how I would go about registering 12000+ accounts from a CSV file? I collected pre-signups as I developed the website over the last few months, now I need a way to get all the accounts into wordpress and activated, with a randomized password.

I don’t just want to send an email out to all people that signed up to register as the presign up process was relatively lengthy (2 mins) and all the meta data I need is in the csv.