got it!!!
I found that it is not necessary to do the include of the Extra Field module itself... all that is needed is to add the specific Param field to the cart.tpl file. So I added this:
Code:
{$products[product].param01}
directly under the product description like this:
Code:
{$products[product].descr|truncate:150:"...":true}
{$products[product].param01}
This works great and gives me the functionality of a download cart. I hope that someone else can find this useful also.
Cheers.