Below is routing and how to relieve tension on tensioner to install belt:
everyone has their personal way of routing the belt as far as which pulley to route it over last. I personally route the belt around all the pulleys, including the tensioner pulley, except the alternator pulley.
Holding tension on the belt with my left hand at the alternator, i use my right hand to rotate the tensioner pulley with a breaker bar and then slip the belt over the alternator with my left hand. Seems to work easiest this way for me.
Sorry, forgot to add that part. You will need to remove the cooling fan and cooling fan stator in order to put the belt on. Labor just to change the serpentine belt is 1.8hrs: