04FN switches to DVD if I recall correctly.
You enter the two characters for the function number followed by FN. So a total of 4 characters. Is that what you are sking about?
That needs to be followed by a carriage return/enter command . Crestron's is /r ... I don't know Nevo's.

I saw that you are controlling a PDP as well.
PDP uses a straight pass-through cable. All other Pioneer components use a null-modem/crossover cable.