Need help creating login menu item

If you're talking about the look and feel of the modal popup, the sourcecoast theme is included with the SCLogin module. You can select the theme in the settings area of the module.

If you're talking about how the menu behaves (like after you're logged in), we describe the behavior in our common support questions for "How can i open the SCLogin Modal Popup with a regular link?" > Add a menu item section.

Both portions are the SCLogin module.

* The login / register links are set up using the Login View Settings: Login View Settings > Modal Popup and Modal Style > Text
* The menu is done using the Logout View Settings: Show User Menu option.
* We wrote our site template, so the module is just styled to look like it's part of the menu.

From that link I provided

On sourcecoast.com, our Log In and Register links are not actually part of the menu. We are using the SCLogin as a module and displaying in a template position near the menu. The module has then been styled to have a consistent look with the menu and is set up to use the 'Modal Popup' view type and 'Text Links' to launch the modal.