Installing An Aftermarket Amplifier: How To Do It?

[gs_1993]

I own a 1993 Gs 300 with the stock Pioneer amplifier. I'm trying to swap it out with a 5-channel car ampifier by Boston (4 channels for the speakers, 1 for the sub). I don't care about wattage ratings right now, my only concern is how to install it. I ran the power wire already to the trunk, as well as a ground wire. I bought a pair of crossovers for the front woofers/tweeters, as well as high frequency blockers for the rear midrange speakers (I will be running the amp on high pass for the speakers). My MAIN question is, how do I connect everything up? There are 3 little white plastic plugs with various wires going into them that plug into the stock amp. I'm guessing the stock amp gets a signal from the volume knob on the dash, gets another signal from the 12 disk cd changer, and outputs to the 6 speakers and subwoofer (2 tweeters in front, 2 midrange in front, 2 midrange in rear). Now all my boston amp needs are RCA signal cables, and a turn-on lead wire, as well as the speaker wires (which will be easy to connect to the amp). How the heck do I connect everything else up?