Custom post template

Is there a good tutorial out there that explains how to make custom post templates for the back-end?

I’m not talking about a theme page but an actual custom form for the back end. For instance a “Add Home Page” which would extend post-new.php with a bunch of custom fields and not the regular content area. Basically like chapter 7 of the WordPress Plugin Development book but a little more than just an image. I’m sure there’s a way to piggy back on the built in post-add and post-edit templates.

oh and not a plugin, I want to learn how to make templates. Thanks in advance.

Dan