Replace "add to cart" with "download" for free digital item

hello there,

I know its possible to rename the "add to cart" text button with another text like "download" , I am wondering is it possible to make the button link them to the download file that is attached to the product instead of placing the product in the cart ?

Lets say I have a product that is price at 0.00, instead of having the customer log in, click the "add to cart button" and check out , they can just click the rename " add to cart" button and instantly download the file.

Let me know there is already a mod out there that does this but I have missed.

Thanks
Ang