I don’t think anybodies ever really done it, but it’s definitely not going to be a plug and play thing.
Depending on your Physics Engine you might be able to integrate it as part of your project, and then create an Actor Component that references it. That’s probably easier than completely replacing the Engine’s physics system, as it’s pretty rooted in. Not sure where to begin though, you’d at least have to bypass the physics engine/collisions in Unreal first. Easy enough if you set everything to have no collision 
Simulating stuff shouldn’t be hard, it’s the collision side that’d probably the toughest bit.