Attention car stereo experts!

On long trips, I like to use my laptop as a DVD player to entertain the
kids. Because the volume on my laptop was inadequate, we used to connect
the headphone jack of the laptop to the cassette player in the car (using
one of those cassette-like converter cables) so that we could better hear
the movie using the car stereo speakers. My old car is gone and my new
Saturn has the CD/MP3 Player.

Is this possible to input sound from an external device with the Saturn
CD/MP3 Player?

There are no audio input jacks on the player itself, but has anyone out
there ever pulled out the CD/MP3 unit to see if there is a way to wire in an
external jack? If so, please let me know. Having a CD player is much
better than a cassette player, but being able to input audio was a feature I
liked with the cassette player. Hopefully there is a way to get it done
with the CD player as well.

Thanks in advance.

--
K Russell
Mechanicsville, VA