Generator Prep Wiring

[Rexerito]

I know that this topic has come up before but I cant find the answer I am looking for when searching. I have a 2021 Montana Legacy with Generator Prep. I am looking to add a portable gas generator (Onan 4500i) with this slide out tray

in the generator prep bay. My question is... Does anybody have the wiring to the generator prep box in the basement? I need to understand how to wire it up to a 50 amp or 30 amp wall outlet, so I can plug in the generator. (I dont want to use the shore power plug. Want this to look clean. Thanks in advance!