So, good news. I talked with Mitsubishi Consumer Relations (949-830-8364) and they got me what I needed for both HDMI and other inputs on my new WD-65731 TV. Essentially you need to take the original Mits remote and hold down the power button until it blinks twice, then input 0,0,0,9,0. This puts the remote into direct access mode. Once in this mode, you can use the original Mits remote to provide the infrared codes for your learning remote, in my case the Harmony 880. In order to provide the learning code for the HDMI-1 input, you press the "Input" button (this does not send out a code but sets the remote up to send out the appropriate code) and then press the F1 button. For the HDMI-2 input, press the "Input" button and then the number 4 button. For a complete list of buttons for various inputs, let me know if you need them and I will publish them. To get your Mits remote out of direct access mode, press the Power button until it blinks twice again and then input 0,0,9,3,5.