Gravity User Registration form avoided by WP registration link?

At the bottom of my site's blog articles is a link for readers to post a comment, and to therefore log in first. Click it and the standard WP login form appears. New users are given the ability to REGISTER using a link provided. How can I change that link such that new, unregistered users get only the Gravity User Registration form I created, instead of the WP registration form? If I'm unable to do this, the Gravity User Registration is all but useless, since most users would bypass it.