Customize Joomla Component AEC (Account Expiration Control)

I want some modifications to the excellent AEC (Account Expiration Control) component for Joomla (1.13) Currently, a user must register for a Joomla user account, THEN buy a subscription. I want this reversed, so that if they do not have a user account already or are not logged in, they can pay FIRST, then the system will automatically register them to Joomla, (similar to MosLock by Phil Taylor) as well as assign the appropriate user status (I've created a special access group already using JACL). I also want an IPN receiving script setup for E-Junkie so that users can pay with the E-Junkie cart (which has Paypal and Google Checkout, and supports IPN notification to a custom URL) - and these users would also have a Joomla account automatically setup for them, and receive immediate access to our membership system. Additionally, I want the Joomla registration page altered so that it presents you with the 2 options: either the free subscription, or the PAID subscription option. For the PAID option, they will have 3 choices: 1- pay via the Paypal button already integrated into AEC 2- pay via the E-junkie cart, which supports Google Checkout 3- pay via credit card, through osCommerce (an offline solution) So the gig consists of 3 parts: 1- modify the AEC component to include payment first and automatic account creation 2- create an ipn receiving script that will create accounts for eJunkie users and add them to the AEC system 3- design a new registration page that offers the 2 options, paid or free subscription (I will give you the graphic design layout for this page)