if you check in the official vera "app store" you will see a version of the pioneer receiver plugin there. if you install it from there then simply put in the IP address under the "Advanced" then "Params" tab you will be good to go after reloading luup engine.
also, I have some custom scenes that I trigger and talk to the receiver over TCP/IP (telnet).
local socket = require("socket")
tcp = assert(socket.connect("IPAddressHere", port#))
tcp:send("19FN" .. "\r\n")
tcp:close()
that will switch the input to what maps to 19FN (DVI in most cases).