Anything can be done given the time, money, and expertise. But in this case I don’t think it would be easy.
Only the Model 3 has the internal camera as part of the vehicle. There is no such camera in the Model S or Model X that we know of.
Oh, I see. That makes sense now. I guess OP will need to add an off the shelf camera. Actually, I didn't know the 3 had an internal camera. Good info.
It depends on what you're trying to do. Yes, you can.. there's an input switcher available that lets you switch the rear input to another (extra) camera. Some use it as a front camera, others have installed them in the cabin (e.g. watch the baby, or a pet). @artsci and @BearBu have the products that can assist... However, if you want to use it to record to TeslaCam, then, no, I don't believe either systems will do that.
I think I remember teardowns showing the AP2.5 computer board had a "Selfie" camera input so you should be able to plug in a Tesla camera to that but I doubt it would enable software support automatically.
The Model 3 AP2.5 computer does have a selfie port, but the S/X 2.5 APE computers do not. However, the S/X APE3 (“FSD Computer”) units DO have a selfie port, which isn’t currently wired to anything. However, I’m unsure what the OP is actually considering. Perhaps he just wants an inward facing dash cam? That can be installed for dirt cheap.
