The Hard Way:
Step 1- You have to tear all that junk out from under the sink so you have room to lay down under the sink and work.
Step 2- Close the valves on the water supply lines.
Step 3- Find your favorite crescent wrench, pliers and other necessary implements of destruction and spend the next half hour (or more, or less) getting the hot and cold water supply lines detached from the existing faucet.
Step 4- You can clean up your first mess now since we all know that those water lines, when disconnected and lowered, were of course full of water. Not a lot of water; just enough to get your face all wet and soak the floor of you base cabinet.
Step 5- Now you have to use the pliers or some such similar device to remove those large plastic nuts that look like you should be able to turn them by hand. But you never can, simply because you can't get any leverage on them. This is about the time that you really begin to appreciate the lack of space. If you have a fiberglass type sink, you might even have a couple nasty little cuts on your knuckles. Joy.
Step 6- Woo Hoo! You can now remove your faucet.
Step 7- At this point I would say that assembly is same as above, in the reverse order. Unfortunately, it's not that simple. You need to go through the blow-by-blow description to fully understand (especially if you haven't had the pleasure of doing this before!)
Step 8- Mount the new faucet on top of the sink, grab those two large plastic nuts and climb back down in the cabinet and thread the faucet down onto the sink basin.
Step 9- Grab said Channel-Locks or whatever pliers you have handy and tighten those nuts down enough so you are comfortable that it will be just as hard for the next guy to take them off as it was for you about an hour ago.
Step 10- Re-connect the hot and cold water lines. Since you only do this once every five years or so, you totally forget the pipe thread tape that is required to ensure a water tight seal. You spend the next half an hour inventing new cuss words because you can only turn the connection hardware abut .023 turns because there is no room between the sink basin and the back of the cabinet.
Step 11- Now, if you actually did forget to put the Teflon tape on the pipe threads, you can go back to step 3 and pick up from there. Otherwise, bravo, you can pick up here which is the next correct step.
Step 12- Climb back out from under the sink and go find your tape, which is hopefully right there on the counter where you left it.
Step 13- Climb back down under the sink and try to wrap that pipe thread tape around the hot and cold water pipe threads. Of course there is not enough room! That would be to easy. So you spend the next 10 to 15 minutes trying to wrap enough tape on the pipe threads so that you won't have any water leaks. You know this is a critical step because you DO NOT want to have to disconnect anything under your sink ever again. Ever.
Step 14- Reconnect the hot and cold water supply lines. It is at this point when you will realize if you put that tape on in a clockwise or counter-clockwise direction. One way works and one way does not. When you try to thread those lines on, it will make your tape job come unraveled and you can back up to Step 13 and give it another try. When you get it right and both lines are finger tight, you can promote yourself to step 15.
Step 15- Finding your trusty wrench, which I'm sure your dog brought back to you no matter how far you threw it an hour and a half ago, you climb back under the sink to FINISH THE JOB. FINISHING THE JOB takes a long while. You are agitated, you have busted knuckles, but you get-r-done Amen. You feel as one with God, nature, and all things good.
Step 16- Open the valves. Only now will you know if you done good or if the punishment will keep on giving. If this is your first time, you will probably have something leaking somewhere. Or even worse, you will see no leaks, you will put everything back under the sink and three days later, your wife will want to know why everything is soaked under the sink.
Step 17- I think you get the picture. Go back to step one. Do not pass go, do not collect $200.
If you are a plumber, you know this is not a joke. This is partly why people hire plumbers. And I have met several plumbers that have bad backs because of all the time they spend under sinks.
I did the same thing. That is why I invented easySink.