Can catalog be used standalone with integration to a separate hosted cart?

I'm curious if it is possible to integrate zencart with a different hosted cart's back end. In particular, I am wondering if it would be possible to use zencart's catalog and presentation functions, and integrate add to cart and other links from a separate, hosted cart instead of using zencart's own cart functionality. Then the checkout process would funnel to a hosted cart elsewhere (bypassing all zencart checkout functions). If these elements are all strictly database configurable then it probably wouldn't fly.

Has anybody used only the catalog functions as a standalone in this manner?

If this is not doable with zencart, is anyone aware of off the shelf components that would present only the front end catalog portion and allow for templates/customization?

Thanks in advance!

For security reasons Zen Cart uses sessions to control things. The individual functions rely upon the session and are not meant to be used piece meal or as modules

For curiosity's sake- Why would you want to use another checkout/backend?