Thanks for the info.
I see that this is one possible solution for my problem, but... it's the same as listening CD's through a radio station. So now I know that few manufacturers like kenwood, sony, pioneer etc. make an "add-on" cd changer, which contains a separate small control unit, which can be used to control the changer and is attached to console. But only thing I'm still missing is the info over bus??
SO if you know what kind of cable toyota uses to control the changer, please tell me! I contacted my local dealer, but he didn't want to tell me more than just, "these days OEM CD/radio is standardized to fit with most of the aftermarket changers...", but no info over the cable!!
If someone has removed an OEM radio from 2004 corolla, please take a pic of the connector that goes to changer. THANKS A LOT!!