how the heck do u take out the computer??!

Take the passenger side kick panel off. It is right there under some insulation. A few bolts, remove the wiring harness, and its out.

Edit: I think what you are looking at is the factory amplifier? Behind the radio.
 
ah ok. naturally its going to wanna come through vertically, which will cause it to get stuck.

reach up with your arm and bend it horizontally and push it into the hole to start it. does that make sense? sometimes its hard to type crap from a computer :D

then pull from the engine bay.