Looking at the manual again that is for a Altum - so a different bike. I apologize but left my post as is for anyone in the future with a edit on it.
I cannot locate a manual for the ESX - however if it truly does have full cable routing which makes sense from looking at pictures (cable enters behind the headtube and then to a direct mount bottom bracket configuration) then it still is not that difficult.
You just prepare the old housing to be pulled through the bike with either a cable/string or new cable being pulled behind it. Ultimatly this is standard work for a bike shop to perform or maybe a level 2.5/5 for a novice in home mechanic.