Try this:
Search for a code to control the volume on your A/V or stereo receiver
1. Cover the end of the TiVo remote control with your hand.
2. Hold down the TiVo and Mute buttons simultaneously until the red (or amber) light on the remote control remains on.
3. Remove your hand from the end of the TiVo remote control.
4. Enter code 1999.
5. After you enter the code, the red (or amber) light will flash three times and then remain on.
6. Press Channel Up once every two seconds. This will test hundreds of codes, one by one. Do not go any faster than this or you may skip over a code that works.
That’s all that’s mentioned on the TiVo site. Hope that helps.
All the best,
Nonoise