Modifying lense shift relative to Vector3 position

Hello, Is it possible to get hold of a Vector2 position relative to a Vector3 so it can be fed in to the main camera's lense shift property? If so would you happen to know how it's done?

Reason being is that I'm currently on the search for ways to replicate a similar effect on Playstation 1 RPG's (such as FF7) where there was actively no perspective shift on the background and the camera just panned across a detailed texture. Except I was wondering if I could just use 3D elements and some camera trickery rather than have to pre-render anything.

So far changing the lense shift seems to produce some interesting results, so thought I'd dive deeper in to it.

Many thanks and all the best.