When you say screen, is there a basic touchscreen for the radio, and that's where your seat adjustments are made? That's cool that the power seats can be adjusted there, but I imagine it would also control a whole bunch of other stuff and would be unwise to remove it.
In a 2013 I'm guessing just about every function in the car is operated though the CANBUS. So unless you plan to interface with that with ~a lot~ of programming, the physical controls can be controlled though a set of relay contacts controlled though USB. Then you need front end software, like the Fusion brain and it's bits. You could also control the power seats from the relays, if they're operated from the CANBUS, you'd go inside the seat, relocate the factory wiring from whatever I/O module is down there and go into a bunch of relays. (at least 4 standard automotive SPDT relays per seat, two if you use DPDT) One set runs the linear slide motor, while the other runs the angular motor.
... either way you look at it, it's a lot of slicy-dicey for a spankin new 2013.
Another way if you really wanted it done- You'd have to find some who really knows about CANBUS programming, and hook up the car-computer into that... Minimal splicing, but more coding.