there is a commercial mod... costs £39 or $39.. i cant remember which..

i have played with the free version... but i found it conflicted with IH2 even tho others have it working with IH2...

you can find it here but i dont think you'll find much in the way of support.

their is also this

but i find that most people make the mistake of their ZC site becoming more style than substance when using pretty ajax. but thats a matter of taste...

having ajax wont make people want to buy your stuff.. having a fast site with great products and clean design will help you more! IMHO