Since the VRC 1100 has no learning capabilities you won't be able to use it to control your TV input. The VRC 1100 basically emulates a keyboard on your computer and can really only work as a keyboard.

You could pick up a cheap Harmony remote off eBay for around $50 or less and teach it the commands from your VRC 1100, the TV, and the Roku3.

Something like this: [Link: ebay.com]