Perhaps you could explain in more detail, but my suspicion is it's not possible.
I have a page that i want to use as a template. It's got placeholders for images, etc... But occasionally, I catch myself trying to edit the Master page. I'm just trying to make that page uneditable, so I don't have to keep re-editing the Master. I can elaborate further if more details are needed.
Are you saving with the .indt extension? When you do that ID will open an untitled copy by default so that you don't accidentally overwrite your template file. I'm not sure what to tell you about editing the master page other than one, be more careful about where you are, and two, perhaps lock the objects, though that may have adverse effects on your ability to use them for placing content.