Yup. Check out this link for a how to.
From that link:
Programming TV power, volume, and mute
You can program your TiVo remote to turn your TV one and off, control the volume, and cycle through the TV input settings, so you only have to use one remote to control your TV.
Show the steps
1. From TiVo Central, select Messages & Settings > Settings > Remote, CableCARD, & Devices > Remote Control.
2. Highlight Part 1: TV power, volume, and mute and press SELECT. The DVR displays a list of television brands. Use the UP ARROW and DOWN ARROW buttons and the CHAN DOWN and CHAN UP buttons on the TiVo remote to highlight your TV brand and then press SELECT. The TV Remote Codes screen appears.
3. Follow the instructions on this screen to enter a code into your remote control. If the first code does not work, repeat the instructions to enter the second remote control code, and so forth, until you find a code that works.