Usually takes around 2 hrs. As stated, intake does not come off. They may have told you that as there is some Chrysler engines that it does have to come off of to change plugs.
Do not use any kind of Bosch platinum plugs, I have seen major running problems with these and a few other platinum brands. Stock plugs work the best.
It's not a hard job to do if you have the correct tools, but with the swivels and short extensions required you need to be well equipped in your home garage. Power tools help to speed things up.