I know/strongly believe it can be done, but does anyone know exactly what mods and how?
Thanks,
Jeremy

Assuming that the seat and its rails fit into the space on the floor (they most likely do) you would just have to mount the new seats rails in the old seats place and install the seat. You could probably wire the new seat in as well, but unfortunately thats not my expertise.

You also have to consider the power harness connector (is it the same or not?), the memory connector if you have memory seats and the airbag sensor (at least for the passenger side). It could get ugly but it should be doable.

Bob

Unfortunately I don't have access to an s4 so I can compare the floor pans and wiring harnesses. I put out a request for local assistance on another forum with no response. I think that would be a good place to start.