I have read that you have to use addfac.

Also read you ONLY have to raise the NPCs disposition using setrelationship.

Then I read that you ALSO have to set the disposition of YOURSELF to that NPC.

How exactly is it done? Can someone give me the proper steps?

You do know that anything you do in the console will not be save for the next game? All this effort is per session. Even then, if the NPC does not have any of the Follower/Companion Scripts assigned to them, then they are pretty much useless as a follower.

Get a mod if you want to make non companion NPCs companions. At least then, there is a chance the NPC will actually be a companion, rather than something that just follows you around.

The NPC that I am trying to perform this on, does indeed have all of the dialogue voice files, etc.

Please explain more as to what you mean by "next game"?

Everything that I have ever done in the console has held.

I added multiple items to my home using placeatme and they have held for weeks.

Also added the unobtainable horse, Karinda to my game using placeatme and it has never disappeared.

Please clarify.