rack and pinion assembly....

alright, where to start... i need a new rack and pinion assembly and i know they have them on 3sx for like $400. my mechanic wants to charge me $2200 to get this done, but thats a lot of money that could be spent on other things. want i want to know is, is this something that is possible for me to do? (keep in mind im not a pro at this stuff, just basic knowledge) how long would it take?, what level of difficulty?, and does anyone know of any walkthroughs for it? i would love to be able to put the extra $1800 towards something productive.