Sorry. I completely misunderstood what you were looking for.

There is a post several threads about Samsung TV's and a code search. The OP posted tons of hex codes, but stated at the end that he was unable to find discrete USB input calls.

If you look through the thread, you will see that he posted 3-4 different, unique codes that brought up the smart hub. You could try those codes and see if they perhaps had a different effect on your TV?