MP3 CD Changer Added to 2003 GMC Envoy

I have added a cd changer to my 2003 Envoy with bose. I an accessory wire from the ignition. However when I turn off the car the changer turns off and the radio stays on for about 15 minutes. What wire can I tap off of to get my changer to stay on with the radio when I remove the key?

Marlon, where did you put the changer?? I want to put an mp3 changer in my Envoy XUV. It can't go in the cargo area, and I want to put it under the seat. One dealer told me they couldn't and one said "sure no problem" makes me wonder.

I've got mine in the read cargo area under the rug that removes. The door that opens up under that rug is where I have my changer. I can close the door perfectly with the changer in there. You would never know it's there. I will try to take and post a pic.