Adding a product to the cart from an external source

Hi
My client wants to sell loose diamonds on her site from a supplier.
The supplier has provided their system to be displayed in an iFrame.

They then say that diamonds can be added to the opencart cart by way of the url they send to the cart url with various variables in the url.

The product will not be in the opencart database. I need for the prod id, sku, description and price to be sent to the cart and paid for.

These are the instructions from the supplier.
In order to connect the embedded search to your shopping cart, you should use the 'Absolut URL'.
Here is the code of the embedded ver. with the Return URL:
<iframe frameborder=0 src='http://onsite.idexonline.com/?Return_Absolute_URL=Your website Return Page&Code_User_From=AAAAA&d=' style='width:890px;height:1000px'></iframe>

Code_User_Form = is a must parameter, if you enter an absolute URL. You should put there the user ID of the visitor (your customer under login). It is like 'Account identifier' ; We wrote there 'AAAAA' - just for example.


Is this possible with OPencart Currently using 1.5.2.1
Thanks