WP e-Commerce Custom Login Page

I am using the WP e-Commerce plugin on my website, and I would like to have a separate file load the login template part instead of the default page.php, so that it won’t interfere with the layout of the other pages. I want the layout of the login page to be different, and unfortunately editing the template part isn’t sufficient since I want the header to be different.

I hope I was clear enough in my description; I apologize for my English.

Thank you in advance.