1. What is Moco for LUA, anyway ? This is a native MIDI firmware for atmega8u2 on Arduino Uno.
You can replace original USB-to-serial firmware with Moco. This driver will bridge between USB-MIDI and serial-MIDI.
(1) The host will recognize Arduino Uno as USB-MIDI device without any driver on MacOSX and Windows XP.
(2) You need to write original USB-to-serial firmware back to 8u2 for the reprogramming of main CPU.(atmega328)