Add PayPal Express Checkout to Interspire Shopping Cart

We need a coder to integrate the PayPal Express Checkout module into the PHP-based Interspire Shopping Cart. The payment module needs to be fully integrated, so that it and its options are selectable in the ISC Control Panel, just like the other payment modules. When the module is enabled, the PayPal Express Checkout button should be visible in the shopping cart page and align properly with the other buttons, such as Proceed to Checkout, Google Checkout, etc. When enabled, all customer and admin notifications should work properly. You can find ISC documentation here [login to view URL] You should be familiar with PayPal module integration requirements and documentation.