the best place to start looking is over at elitecaraudio.com
They have a tutorials section (also called install clinic) I belive. The articles are written by Steve Head (audionutz) He is a very knowledgable guy, and if he writes it you should take notes...If you really want to do this correctly, take some time and read all of his clinics, but especially the ones titled "What is SQ", and the kickpanel FAQ....both are excellent reads...I read both at least 3 times through before I started my kickpanels.
I also highly recommend that you go and buy and IASCA CD. IT will be very helpful in helping you to determine the proper placement for your drivers.
Personally, I think that a simple three way setup (tweet, mid and sub) is one of the best setups to go for in a car. Less is more in this case.