Merchant Manager,OSCommerce and PHP

Hi friends,

I want to know whether anybody is having an idea about how to get (see or download) the code for Merchant manager. If it is possible how it can be done.?

My scenario is like this, i want to host the site with mechant manager which provides online tools for building catalog. I want to add some more functions to that catalog which i made using my own PHP file. Can i integrate it with Merchant Manager catalog and use it ? Can i download the merchant manager code and make changes to it? Hope to see some reply from the members,

Thanks