Mobile scanner installation

I am tring to run the output of the output headphone jack on my handheld scanner to my Explorer's audio system.  The little speaker on the handheld is just not enough to hear.  After scouring the internet for hours on schematics for the OEM radio for the 1995 explorer I came up empty handed.  The idea I had was to use the output from my cassette deck as a means to be able to hear my scanner through the car's audio system.   I know I will have to trick the radio into thinking there is a tape in the deck to be able to pull this off. Any suggestions would be greatly appreciated, and before it is suggested I have tried one of those cd adapter cassette's and it doesn't work if there is no audio coming from the scanner the tape just flips to the other side and then ejects.  I have also tried the fm transmitter and that failed to.  So if anyone can provide me with the scehematic or an idea where to start I would be truly greatful.