There is no way to make links in Photoshop for Encore menus – you must link buttons in Encore.
That said, in Encore 2.0 and later there is a Chapter Menu feature that automates this process.
Keep in mind the DVD-Video format limits 4×3 menus to 36 buttons per menu, and 16×9 menus to 18 buttons per menu. There is also a chapter limit of 99 per timeline. Which all means you will have more than one menu and more than one timeline.
But Chapter Menus in Encore 2.0 and later automate nearly the entire process.