How do I customize permalink structure for custom post type?

Hi there, I'm using custom press plugin. created a cpt called "product" but I can't find a way to have a permalink in a form:

http://www.domain.com/product/%post_id%

If I change general wp settings for permalinks, all the site is affected BUT "product" custom post, which keeps maintaining the structure:

http://www.domain.com/product/%postname%

Could you please help me?

Thank you

Stefano