The osCommerce shopping cart, Version 2.2 or Higher, is 2Checkout Enabled and automatically set up from within the cart admin provided with the cart.
You can find information, or download the osCommerce Cart here: osCommerce.com

You can also look here for more details on installing and setting it up: oscdox.com

The following information should assist you in setting up this cart to work with our service. Please note that we cannot provide any direct support for osCommerce or other third party shopping cart.

1.) First and foremost, you must have the cart itself installed properly. There is a text file that is distributed with the cart, as well as the module mentioned in step 3 below, and this file will explain how to install and set up the cart and module. Please first verify that the installation of the cart and 2CO payment module are correct.

2.) You must be using osCommerce 2.2 Milestone 2 or later. If you are using any other version, it will not work and you will be unable to use our services. If in doubt as to the version currently running on your cart, install the latest version.

3.) There is a module that has been developed for osCommerce that is needed to work with the 2CO system. This module is absolutely necessary to be compliant with our 2CO system. You may find this module at the following URL: http://addons.oscommerce.com/info/5343

4.) To insure that the osCommerce shopping cart is updated when a successful sale is placed, we recommend that you select the “Header Redirect” return method on your 2Checkout Site Management page.

There is also a known issue that osCommerce has alerted us of. The osCommerce cart requires ‘Force Cookie Use’ set to ON. This means that web Sites using a shared-SSL cert will not work. Most problems with the osCommerce contribution are due to cookies not being set up properly and there unfortunately is not a work around for this.