I wanted a set of foot pedals for selecting Escape and other modifiers, and with an analog input for commanding mouse scrolling, so I built a MIDI to USB HID device with a Teensy 2.0 board and a FCB1010 MIDI foot controller. It works ok, but the ergonomics are sub-optimal for use while seated. Perhaps with a standing desk it would be better.
Setting UBRR1L = 32 with the 16 MHz clock configures the UART to exactly the MIDI 31.25 kbaud rate. A resistor between the current signalling pins on the MIDI OUT changes it from a current signal to a voltage signal so that the UART on the ATMega32u4 is able to read it.