I have the discrete codes you are after i will send them in .ccf format. As you already know Denon forgot to put these buttons on the remote that came with the 3801 so I got them off an older remote belonging to a customer and tried them to see if they worked on my 3801. They arent discretes(direct source selection) just toggles. Hope they help.
"Some may never live but the crazy never die" ~ Hunter S. Thompson "There will be plenty of time to sleep when I am dead" ~ Me