What type of installation are you looking to do? Is is just a sub and an amp? If so be careful of the size as not to drown out your factory mid's and high's. Also to minimize trunk rattle. Do you have a good after market deck with pre-amp outputs? I suggest this. Let me know if it's just a sub and an amp that you want details on and I'll take some pic's of my install on my 07 Forenza.
I installed my amp on the back of the 60 folding seat. Ran my 4-gauge power wire down the drivers side through the same rubber boot (after a small cut) as the steering column through the fire wall to the battery. Always run the jacks/remote wire on the opposite side of the power as to cut down on noise interference therefore the passenger side is the logical choice. Everthing else should just be simple wire hook-up and mounting. Don't forget the in-line fuse in the power wire sized per the wire used to power your amp. I normally go with a 60 or 80 amp fuse (just me). Check out my garage for some pictures. WB if any questions.
If any one still needs a guide, let me know and I will put together pictures and a how to, based on my 2007 Forenza, See sig for my system info. I am a installer for a retail store, I do this every day, my methods are professional, I do this every day. Also be specific on what you are wanting to do, 4 speakers, just an amp, two amps, etc, be very specific.