2005 hummer h2 bluetooth

Im having trouble with a 2005 Hummer H2.  I am installing a bluetooth kit into the vehicle and I am stuck now.  I know that there isn't a mute wire in the factory harness, so I have read up online and saw that a few people have used a relay to turn off the factory bose amp and allow the audio to come out of the speakers.  My problem is that the mute wire from the bluetooth unit is 0.05 volts.  How do I convert it to 12 volt to trip a relay.  I have been installing car audio stuff for over 6 years and have never had this much of a pain with a car.  If any one can help me or has a diagram of what to do with the relay please let me know.