http://mark.orbum.net/2012/11/21/google-tv-via-the-vizio-co-star-an-android-cord-cutters-nearly-wet-dream/

I got the video to work to my 55 inch Mitsubishi WS-55315 television by using a DVI to HDMI adapter. I had it hooked up to the MonitorLink/DVI which connected to the HMDI input side of the Co-Star. But alas my computer guy downtown told me that there is no such thing as a RCA/HMDI adapter which if there was would take care of my audio problem. I was doing fine till I hooked up my Magnavox MBP5320F Blu-ray Disc/DVD Player. Actually, the Co-Star found the Blu-ray player and even worked with the Linksys 2.4 GHz 802.11 Wireless -B Broadband router so that the Co-Star and Blu-ray player had separate IP addresses. I just had to have them on different Inputs. The Nvidia 9500 GT video card works with the Co-Star with another DVI/HMDI adapter on the Co-Star end. Since I am running Ubuntu Gnome 13.04 I am enjoying after I installed Unity the drag and drop option without using the Co-Star but was amazed that the Co-Star works with the Ubuntu Gnome 13.04. Just no drivers like it would if I was using Windows. But with the USB to USB cord connected to the 686 computer I am able to load Apps via Google Play from the computer to the CoStar. Since I don't have a cable box or sattellite box I think I am in the same boat as you are.

Kanex DVIRLHD DVI with RCA audio to HDMI Converter is the answer I want to try.

https://www.hdwise.com/dvi-with-rca-audio-to-hdmi-converter-dvirlhd.html?&gclid=CN-224TLm7cCFclj7AodrlkAog