-DnR-Rad

I'm going to be cooking up some electrical projects on my jeep, and i've got some questions which google doesn't answer right... :-\ I'd very much appreciate if anyone could assist in their opinion! I'm an EMS Worker and Volunteer, so I've got a Uniden BC350C Base Scanner, which I'm wanting to place in my jeep. Now I already have six speakers throughout the jeep, and getting another one just for the radio doesn't seem all to efficient. So the question is, I have a standard radio which hooks up to those speakers, Could I splice a mono jack from the Scanner to one/multiple speakers and be able to "overlay" the scanner's traffic on top of my music being played on the stereo? Oh, and i'm enjoying all the cool threads on this forum!