Incorporate user authentication / session handling into a website

We need someone to incorporate user authentication, with session handling, into a PHP-based website we are designing.

We have the bare structure of the site in place but need someone to incorporate users into the existing framework.

The finished project will entail:

- User authentication (email + password)
- Storing details in MySQL db
- Using sha512 or better alternative
- Session handling (login/logout/timeout)
- Interfacing this with our html / php site

Knowledge of the following will be necessary:

- PHP
- MySQL
- JQuery
- Apache
- CSS
- CMS

We would like this work done in 1 week. We will be able to answer questions by e-mail throughout.