Check out the fabrication section, I beleive there's 3 different mounting options listed. I mounted mine on the roof between the sun visors and ran the antenna out the back by the rear glass. There's no right way or wrong way it's personal preference.
As far as CB's are concerned, I picked up a Midland 1001z ($27.99) which is a small unit and it has RF gain & Squelch knobs, PA switch, pa output jack and external speaker jack and Instant channel 9. Can't beat it for the price.
Just like another poster stated a handheld CB will work just as well and you can even magnetic mount an external antenna to the roof (nothing permanent).
Also a few of the members will be bringing there GMRS/FRS radios with them also. That would be another option for you.
I used this fabrication thread (my pics were added there also):
http://www.jeepkj.com/forum/showthread.php?t=38404
First thing to do before you purchase anything is Google it my friend for reviews.
If you want specifics on my install PM me.