OWA custom login

Hi, I want to use custom login form (with DB or file) in order to login to OWA. I want to have a login form where i'll insert username and password, it will check the username and password (in DB or file)and will convert it to OWA username and password (also stored in DB or file) and will make the login to the OWA. for example username:user1 , password:user1 and it will redirect to OWA with other username and password after conversion (from DB or file): user123, password123. Please let me know how to you think to do it. I need it to be ready in 24 hours, and instructions how to put in on my server. I'll pay after it working on my server. Thank you.