I’ve created the following tutorial in response to topic 47148: osCommerce and WordPress at WordPress Support.
While I have been programming PHP for a while, I am new to both OS Commerce and WordPress. That being said, for this integration I have tried to follow the coding standards for creating a new OS Commerce page. If you see any refinements I need to make to my code, feel free to comment. I hope this helps all of you who are looking to integrate OS Commerce and WordPress.