Well I think you are missing a few buttons first of.. but here..
analog -> analog
digital -> digital
x -> b
a -> a
y -> c left
b -> c down
l -> l
r -> r
then you have those two button on you 360 to the left of the digital. use one for c right and one for c up. You still need on for trigger and one for start, but i dont know whats is under the 360....
If that silly X logo is a button use it for start.. If the analogs have button functions (pressable) then use them.
All and all its not a good set up for n64, get a usb adapter for 10 bucks and a used n64 for 3?