Hi,
Where do you want to show the non-cart attributes custom fields? Above the add-to-cart button?
All of our templates use the same concept. We are using "TAB" to put the non-cart variants. It is called "Specifications" (but you can translate the word of Specifications to your native language through language file).
Putting the non-cart attributes inside the Specification TAB's will also increase the user-experience, avoid miss-understanding for your buyers and eliminates the mess in the product page.
For more info about how to create Specification TAB, look at the tutorial.pdf:
www.flexiblewebdesign.com/media/tutorials/coolmart.pdf
and read the last 2 pages.
Regards,
Support