Can I use just the shopping cart function on my site?

In order to make the most customizable store, I want to mainly pull out the add to shopping cart function and use this function on my site instead of installing the whole zen cart itself. I am sure there is a way to pull this function out. Can someone please help?

Thanks.

This is not how ZenCart is designed. It is meant to become your site.
It can not be seperated into pieces or be made modular mostly due to the many security inter-reliance functions

They can do a hard coded link to each product and be basically same thing except using html to the checkout part of zencart and still be in the zone of zencart zenid showing, but ssl would be definitely recommended for encryption somewhat like a few websites I have seen on the net.