Zen Cart Customization Project

We have a site that is already built and working on the Zen Cart ecommerce platform. We need an experienced php programmer with Zen Cart and XML experience to customize the way Zen Cart works on our site. We need to have Zen Cart linked to another site and will need to perform as follows: When customers on our site add something to the shopping cart instead of it being placed in the Zen Cart shopping cart it will place the item in our virtual vendors shopping cart by passing an XML document to the virtual vendor website. From there all functions needed for purchasing the product will be handled on the virtual vendors website. The virtual vendor has provided extensive documentation and online resources that include XML examples and code simulators to assist in the linking of the two sites. I have included a document that gives you the virtual vendor process overview. Sorry for the quality of the document, my scanner is broken so I had to take a picture with a digital camera.