var input[2];
#define key_jump 0
#define key_shoot 1

function handle_input() {
if(use_xbox) {
input[key_jump] = scan code from joy_5, see "key mapping";
input[key_shoot] ...
}
else {
set input[] key_board scan codes
}

Then in your functions:
if(key_pressed(input[key_shoot]) && ...) { }