modifications to factory 2000 celica radio

[zkajan]

Hello
I want to modify the radio that came with my 2000 Celica. Not buy a new one, I like this one, but modify this one. This is what I'd like to do, you tell me if it's feasable. I want to drill a path from the radio to the glove compartment (without damaging anything in-between of course), and make a 1/8" stereo plug (male or female, doesn't matter) be on the inside of the glove compartment. The other side of those leads i want to connect to the radio such that one of the front buttons activates that as input, preferebly the AM (which I never listen to) one. Basicaly, press CD to play the CD, press tape to play the tape, press FM1/2 to play FM, and press AM to play whatever is plugged into that plug in the glove compartment. Yes, I have tried just using one of those "use your tape deck as cd player"-tapes, but then i have the sound of a spinning tape if i play it loud, not to mention a nasty looking wire running out from the tape deck.
I am aware that this may require opening the radio unit itself, soldering, or even re-programming an EEPROM, and feel comfortable doing such tasks.
With that said, how feasable is it to do something like this? Anyone know where I could find board diagrams of the boards in the radio, or even perhaps (and now i know i'm asking for a lot) source code (probably assembly) for the chips running the show in there?
I really want to avoid spending money on a new radio especcialy if i can make a fun electronics project for myself for a few weeks.

Thanks a lot to any and all replys.

[Zrain]

Save yourself the pain and just get an aftermarket 4 CHN Amp and a 2 Chanel AMP and just bypass the radio all together and just set up a amped 4 speeker and 2 sub Stero. then wire up a flipswitch to swtich the Amp's RCA imputs from the head unit to the 1/8th inch jack.

and dont say THATS TO MUCH MONEY!!!

dude if u want a costom Imput you need to Imput some money into this.. theres other gheto way's of doing this but if u ask me this is the only good and respectable way of doing this.. i dont condone any other method.