All I want to use is the shopping cart and 'add to cart' buttons...?

[odecom5]

Hey. I have just recently set up a new website for a client and now that I am finished with it he is just getting around to telling me that he wants his own shopping cart software installed rather than using PayPal's. The trouble is, I already have the product pages, and I don't want to have to completely rewrite the template for zencart just to fit my pages. Is there any way that I can just add custom 'add to cart' buttons on the pages I already made and place a shopping cart on another page? I really don't want to be spending another 50 hours customizing this.

Thanks for your help! I'm sorry if this question has been asked before. i'm a helpless new guy

edit. i don't want to use categories or dynamically upload products and info into the page. it is a very simple thing, he only has three different products, so it seems useless to have all that extra stuff in there, since it won't change...